Known trinkets are as follows:

- **???'s Soul*** - Provides a familiar that shoots homing spectral tears. Other familiars may follow him.
- **Ace of Spades** - Improves chances of finding cards
- **Bloody Penny** - 50% chance of dropping 1/2 heart upon picking up a coin
- **Burnt Penny** - 50% chance of (collectable) bomb spawning when picking up a coin
- **Cain's Eye** - 25% chance of Compass effect at the start of a floor
- **Cancer** - Doubles current tear stat
- **Child's Heart**  -Increases the chance of receiving hearts from drops
- **Counterfeit Penny** - 50% chance of increasing coin value on pickup
- **Cursed Skull** - If Isaac's health is brought down to 1/2 of a heart, he is then teleported to a random room
- **Curved Horn** - Increase damage
- **Eve's Bird Foot** - Chance to spawn a Dead Bird when attacking an enemy
- **Fish Head** - Attack flies spawn every time Isaac gets hit
- **Flat Penny** - 50% chance of spawning a key when picking up a coin. May rarely spawn a golden key. 
- **Goat Hoof** - Increases movement speed
- **Isaac's Head** - Provides a familiar which is similar to Brother Bobby, but with piercing tears
- **Isaac's Fork** - When clearing a room, provides a 10% chance of healing half a heart
- **Judas's Tongue** - Items in the devil room only cost 1 heart (only works if picked up before entering devil room, and items requiring soul hearts will still require 3 of them)
- **The Left Hand** - Replaces all normal and golden chests with red chests
- **Liberty Cap** - For each room, 25% chance to give Isaac a random passive mushroom-based effect. Can also give The Compass effect (cited as a bug on wiki).
- **Lucky Toe** - Increases chance of an item dropping after clearing a room
- **Maggy's Faith** - Gives an eternal heart at the start of each floor
- **Match Stick** - Increases bomb drop chance
- **Missing page** - 5% chance of invoking Necronomicon effect when receiving damage.
- **Mom's Pearl** - 10% chance of red hearts spawning as soul hearts instead (stacks with Mitre)
- **Pinky Eye** - 10% chance to fire a poison tear
- **The Polaroid** - If HP is half a heart, or receiving damage that would reduce HP to half a heart, Isaac receives a brief damage shield and HP is not reduced. Also allows entrance to "The Chest" when opening the big golden chest at the end of Cathedral.
- **Push pin** - 10% chance to fire a spectral tear
- **Red Patch** - Chance to activate the "Razor Blade" when hit
- **Rusted Key** - Improves key and golden key drop chance
- **Safety Cap** - Improves pill drop chance
- **Samson's Lock** - Chance of increasing damage when an enemy is killed for the current room (similar to Bloody Lust)
- **Tick** - Boss health decreased by 15%, 1 heart restored when entering a boss room. Cannot be replaced (be careful picking this up).
- **Umbilical Cord** - If brought to half a heart Little Steve will be spawned

Some info has been taken from [The Binding of Isaac Wikia][1].

  [1]: http://bindingofisaac.wikia.com/wiki/Trinkets