According to "The Cassel Dictionary of Slang" "Crack-Corn" referred to White People and originally meant the White natives of Kentucky. It was apparently a variation of "corncracker" which meant a poor white farmer and was apparently applied to the natives of Florida, Georgia, Kentucky or Tennessee possibly because of their dependance on corn or maize. Corn in the British Isles refers to wheat, oats or barley as distinct from the American meaning.