The one's with known effects are as follows:  

- **Cancer** - faster firing speed
- **Counterfeit Penny** - gives a chance of one extra cent being collected upon picking up a coin (dimes might be 11, nickels 6, pennies 2)
- **Goat Hoof** - Randomly causes a tear to increase in damage
- **Burnt penny** - chance of a bomb spawning upon picking up a penny
- **Missing page** - When using a spacebar item a random book is used, and chance of activating necronomicon when damage is taken
- **Bloody penny** - Chance of dropping half heart upon picking up a coin
- **Lucky Toe** - chance of extra items when opening chests or from blue rocks
- **Isaac's Fork** - chance to regain health upon kill
- **Liberty Cap** - Random odd mushroom effect each room
- **Push pin** - Chance that a tear becomes "spectral (Ouija Board effect)
- **Tick** - Boss health decreased, cannot be exchanged
- **Umbilical Cord** - If brought to half a heart Little Steve will be spawned
- **Safety Cap** - Identifies pills
- **Rusted Key** - Chance to drop a key when hit
- **Pinky Eye** - Chance a tear will be poisonous
- **Red Patch** - Chance to activate the "Razor Blade" when hit, and sometimes shears
- **Mom's Pearl** - Chance to freeze enemy