Wild Corn spawns naturally in Plains biomes, and can drop Corn kernels when broken.
Corn is a farmable crop similar to wheat that can grow up to 3 blocks high. It drops several Corn Cobs when harvested.
Corn Cobs restore <x> hunger and provide <x> nourishment, they can also be cooked to provide Cooked Corn, which restores 5 points of hunger and provides 1.2 points of nourishment.
Due to the fact that it grows three blocks high, you can set up automated corn farms in much the same manner as you may set up automated sugar cane farms; this can allow you to harvest large quantities of corn without needing to spend time manually replanting the crop.
Corn seeds are known as kernels ingame, and can be obtained by destroying wild corn, placing a corn cob in the crafting grid, or splicing Hybrid Wheat seeds with Lemon Seeds, they can be cooked into Popcorn which restores 2.5 points of hunger and provides 0.2 nourishment points.