Describes your typical midwesterner. A white guy or girl who is large and stocky but in a healthy way. Corn fed women have child-bearing hips and corn fed men play football. Not attractive, but not ugly either, just plain. They're simple, friendly folks, sweet as apple pie, but lack complexity. Make good husbands and wives, but will bore you to death if you try to have an intelligent conversation with one.
Steve settled down with some corn fed girl from Indiana. Now he'll spend the rest of his dull, miserable existence raising kids and mulching his yard.