tl;dr

Plagued Swarm- A thin swarm of plagued magical insects now follows you. You gain disadvantage on all charisma checks requiring positive a disposition towards you, but in combat may command the swarm to attack for 1d4 poison damage as a bonus action. The swarm cannot leave a 15 foot radius around you, and is immune to all attacks. If you are subject to any conditions (blinded, prone, charmed, etc.), the swarm is as well.

Bat's Eye Gem- Grants the wearer 10 feet of darkvision if they do not have darkvision.

Noble's Crest- +1 to charisma checks interacting with upper class humanoids.

Celestial Soul- Grants temporary hit points equal to the wearer's maximum health. When they have been expended the charm breaks. The unique shape means this charm occupies 3 notches.

Song of the Ancients- When you fall below half health, the charm is expended and half of your used spell slots are restored.

Cosmic Pulse- At the start of each of your turns, flip a coin. On heads, you regain 1 hp.

Trueleaf Sprig- When using wild shape, your attacks deal an additional 1 poison damage.

Poem of Barrus- At full health, you deal an additional 1d4 radiant damage with your melee attacks.

Aazidal's Nexus- When casting a spell that deals fire damage, you may choose to have it deal cold damage instead.

Hunter Queen's Crest- When attacking with a loading weapon, roll 1d4. On 4, you may use the bonus action of that turn to reload the weapon if you desire.

Bloodseeker's Crest- Killing a living creature of CR 1/2 or higher heals you 1d6+1 hit points.

Jonathan's Lock- When prone or sleeping, your effective armor class increases by 1.

Doom of Hell- Take an additional 1d6 damage from fiends. For every fiend you slay wearing this charm add it's CR to a running total. You deal half of this total as additional radiant damage when attacking fiends with a melee attack (for example if the running total is 13+3/8, you deal 7 radiant damage to fiends you hit). This total resets if your hp reaches 0, or if the charm is removed from your attunement. In the infernal plane, the bonus damage is not halved.

Fey Slayer- Doom of Hell but for fey and the feywild.

Wet Feather- Ignore the first 10 feet of falling damage. Falling rate slightly reduced. Taking more than 15 damage from a fall pops the charm.

Witchlight Moth- A small glowing moth follows you around, shedding 3 feet of dim light. Only you can see the moth and the light it produces. The moth does not respond to verbal commands, but will remain within 10 feet of you at all times, and can be caught with a successful DC 15 acrobatics check.

Primal Hunger- Eating the heart of fallen enemies will restore health equal to your base hit die (1d6 for a wizard, 1d10 for a ranger, etc.). Plant based food deals 1d8 poison damage if consumed, and no health can be restored from rests. You do not contract any diseases from eating hearts.

Beacon Stone- You always know your direction relative to the last place you slept.

Crablord- You can speak to crabs.

Vile Shape- Wild shape turns into a monstrosity instead of a beast.

Merfolk’s Blessing- You do not expend an extra movement when swimming instead of walking. You require 3 times as much water per day. It appears to be an ornate fish made from bronze.

Feyblood Shell- If an enemy attempts to put you to sleep with magic or charm you, the attempt fails and the charm is expended. Bears the image of a greater fey wielding a shield.

Sweet Heart- If you take an action in combat to eat a sweet food, you regain 1d4+1 hit points. [/u/RhysNorro]

Sweet Horseshoe- You gain the ability to neigh like a horse. A successful DC 17 intelligence saving throw from a creature who cannot see you will reveal the true origin of the neigh to them. [/u/RhysNorro]

Iron Hide- AC increases by 1, but movement speed is halved and you cannot swim.

Lucky Coin- Once per day you can reroll a 1, and you must take the result. After using this, the next 20 you roll must be rerolled and you must take the result. [/u/lucky2u]

Unlucky Copper- You have a -1 penalty to all ability checks. Appears to be an orb of rusted copper.

Raven Rock- You can expend this charm to summon a Raven under your command for up to a day. After the duration has ended or it reaches 0 hit points, the Raven turns into a puff of black smoke which rapidly dissipates.

Divine Shell- May expend the charm to take half damage from an attack as a reaction to being hit by any attack.

Frostbite/Flametoungue/Shockscar/Unholy/Blackhorn Shell- May expend the charm to deal 1d6+1 cold/fire/lightning/necrotic/piercing damage as a reaction to a melee attack hitting you.

Furious Wind- Can make a melee weapon attack as a bonus action when using the dash action, expending the charm.

Strength of the Noble- May expend the charm to deal double damage on a spell or weapon attack as a bonus action, provided your action was used to make a weapon attack which hit. If multiple attacks are made in your action, only the first receives any benefit from this charm.

Spellmaster- May expend the charm to cast a spell at 1st level that you have prepared.

Shield of Stendarr- May expend this charm to resist being knocked prone.

Heart of Mara- May expend the charm to heal 2d4 hit points to a creature you touch.

Breath of Kynareth- may expend the charm to triple your jump distance or double your jump height for one second.

Hourglass of Akatosh- May expend the charm to undo your turn in combat, after which your turn immediately ends, nullifying any influence your turn would have had on the tide of battle. The unique shape of this charm means that it takes up 2 charm notches instead of the usual 1.

Heavy Blow- May expend this charm as a bonus action to make the melee attack you use your action on push the target away up to 10 feet.

Second Wind- If you are fighting with 2 light weapons and use your action to attack with one of them may expend this charm as a bonus action to attack with each weapon, for a total of 3 attacks under normal circumstances. Do not add ability modifiers to the damage rolls of these attacks.

Dragonskin Shell- If you take damage before your first turn of combat, you may use your reaction to expend the charm and nullify the damage entirely.

Healer's Focus- If you know cure wounds and use it in combat, you may use subsequent actions to cast it again on the same target without expending a spell slot. The first action you take after sustaining Cure Wounds which does not sustain the spell breaks the charm.

Mushboom- Can expend this charm to grow an explosive fungus on an arrow or bolt before firing it. On impact, it explodes for 2d6 poison damage within 10 feet, or half as much damage to those who succeed the DC 15 constitution saving throw.

Lord and Lady Stones- This charm has 3 charges. 2 may be expended to cast a spell you have prepared at 2nd level, or 1 may be expended to cast a prepared spell at 1st level. Once all charges are expended, the charm breaks. Th unique design of this chrams requires 2 notches to use effectively.

Wispy Cloak- Can expend this charm to become invisible. The effect ends if you move, typical invisibility ending actions are taken, or 1 minute passes.

Arcane Knowledge- You may expend this charm to cast any scroll, provided you pass the scroll comprehension DC. Even if you fail this check, the charm will still be broken. The scroll does not use a spell slot when cast.

Mindgiver- Can expend this charm to awaken a shrub or similar plant of CR 0. You command this creature, but it rapidly withers losing 1 hp every minute until it dies. It cannot be healed.

Violet Spore- Can expend this charm to summon a violet fungus from a nearby corpse. This fungus is hostile to all creatures (including the wearer of the recently broken charm) and its victims do not spawn additional fungi.

Acid Tongue- When you make an attack action with a weapon which hits, you may use your bonus action to expend this charm. The target’s AC is reduced by 1 until the end of your next turn.

Magician’s crest- You may expend this charm to cast prestidigitation.

Vile Swarm- Choose an enemy. As an action, you may expend this charm to summon a swarm of rats around this enemy. The swarm can only attack this enemy, and if the swarm hasn’t been killed by the time the target dies, they disintegrate.

Charm Charge- May expend this charm to use another charm that has been used. The other charm is then permanently disabled.

Weasel Tooth- You can expend this charm to summon an invisible weasel and give it one verbal command. If no command is provided, it disappears. It will attempt to fulfill the command to the best of its ability. After this attempt it will disappear.

Monk Crest- May expend this charm to restore ½ of your used ki.

Barbarian Crest- May expend this charm to restore ½ of your used rages.

Bard Crest- May expend this charm to restore ½ of your used bardic inspirations.

Cleric Crest- May expend this charm to restore ½ of your used channel divinities.

Wizard Crest- May expend this charm to restore ½ of your used Wizard spell slots.

Paladin Crest- May expend this charm to replenish ½ your used HP for Lay on Hands or ½ the uses for your Divine Sense.

Rogue Crest- May expend this charm to effectively double your dexterity modifier on an ability check, attack roll, or saving throw.

Sorcerer Crest- May expend this charm to restore ½ of your used Sorcery points.

Warlock Crest- May expend this charm to restore ½ of your used Warlock spell slots.

Druid Crest- May expend this charm to regain 1 wild shape use.

Fighter Crest- May expend this charm to regain 1 use of Indomitable or Action Surge.

Ranger Crest- May expend this charm to restore ½ of your used Ranger spell slots.

Living Tether- You can expend this charm to conjure a vine which binds you to another creature within 1 size rating of you that could be reached by a 30 foot vine. For example, a target 5 feet from you on the other side of a wall might still be tethered if the vine can reach through a small chimney or a window. This vine has the same statistics as a 30 foot rope. Neither creature is considered grapple.

Quipper Idol- You can expend this charm to obtain gills, and breathe water instead of air for 1 hour. You must choose either saltwater or freshwater when you use the charm. It appears to be an idol in the shape of a quipper.

Silent Claw- You may expend this charm to deal 2d4 psychic damage to a target you can see within 30 feet that has not detected you. It bears the image of a Tiger’s head.

Vicious Claw- You may expend this charm to deal 1d4 psychic damage to a target you can see within 10 feet. It bears the image of a roaring lion’s head.

Sleeping Eye- You may expend this charm to magically slow an enemy you see within 30 feet until the end of your next turn. Appears to be a closed eye forged from silver, which opens when the charm has been used. The charm then appears to be empty, and does not contain an eyeball.

Image 3. Studies for comb and choker plaque - Circle of Bats, c. 1900