Just a few suggestions for things which certain creatures may or may not drop during an adventure. Haa!
Golden Cowbell- 5% chance of being in a slain cow's inventory. Meat has 10% less chance of spoiling, collect 4 carrots from one carrot plant.
Infernal Cowbell- 1% chance of being in a slain cow's inventory. Ringing this at night causes all nearby cows to become possessed and attack the player.
Diabolic beefsteak- 15% chance of finding in slain possessed cow's inventory. Take this down to hell, and cook in the lava for a challenge. (lures challenge monster when used)
Leprechaun's golden coin- 2% chance of finding inside any container in the world. 20% chance of strange plants to grow on vacant farmland close to your spawn.
Jellybean plant- 20% chance of growing while Leprechaun's golden coin is equipped on player. The jellybeans can be used to attract a large beehive. Place pile of jellybeans on a spot. (source of Honey) or can be replanted.
Mini beanstalk- As above. the beans can be put into tonics to make them 15% more potent, or replanted.
Candylion plant- As above. The flowers can be crushed into a jar of bottled water to create Candylion pop, eaten as they are as a sweet treat, or can be replanted.
Golden Tree- As above. Can be chopped into Pieces of Golden logs, for very slow burning on fires, or can be replanted via golden tree sapling. Also grows golden pears.
Lost HorseShoe- 5% chance of appearing inside barrels in the world. 10% chance of a bow/ crossbow to not consume an arrow/ bolt. 10% chance of any 1 of 2 handed weapon to deal double damage.
Dented Shield- 6% chance of appearing inside chests in the world. 15% of attackers' blows to fling back at them, dealing half original damage.
Coif of the fallen hero- 4% chance of appearing inside chests in the world. when worn, causes a shadow of the fallen hero to come to your aid, but only when player is below half health. Hero shadow abilities could be based upon player abilities, for balance.