Bone meal is an item that can be used as fertilizer, or as a dye.
A bone can be used to craft three pieces of bone meal.
Bone meal can be used by shift-clicking wheat, potatoes, pumpkin seeds, water melon seeds and Carrots (still growing) to make it ready for harvest, red and brown mushrooms to make them giant mushrooms, and a sapling in dirt to make it a full grown tree.
Growing plants on grass
Bone meal can be used to dye sheep white.
It can also be used to make a tamed dog's collar white.
Bone meal is also used as white dye. It also lightens the color of other dyes.