The flower cow is a cow that spreads flowers everywhere it goes. It turns dirt into grassy dirt, grows grass, and turns grass into flowers. It can be bred and tamed with grass. If you have the bonemeal mod, it can be bred with bonemeal, mulch, or fertilizer.
The flower cow spawns naturally, but rarely. Only 1 in 10 cows is a flower cow. Flower cows can not be bred from cows. If you are lucky enough to have a cow in your inventory, you can craft it with a flower to make a flower cow.