Deku Seeds
Deku Seeds are found in The Legend of Zelda: Ocarina of Time. They are common items, especially inside the Great Deku Tree. These seeds are used as ammunition for the Fairy Slingshot. The Deku Seeds can only be used as a Child due to the Fairy Slingshot not having any use as an adult.
They are held in the Deku Seed Bag, which can be upgraded to greater capacities.