i'm a minnesota norwegian, so perhaps you won't trust my cornbread recipe. it has honey in it, and i don't think that's properly "southern". however! it's the best cornbread i've ever encountered. what do you mean by simple? there are more than three ingredients, but no steps to speak of. measure - mix - bake.

1/4 cup honey
1 cup sour cream
1/4 cup milk
1 egg
1 cup yellow cornmeal
1 cup white flour
3 tbs. melted butter (okay, melting the butter is a step, but you can do it in the pan you bake in, so it hardly counts...)
1 tsp baking soda
2 tsp cream of tartar
1/2 tsp salt

bake it at 425 degrees in a 9 inch cast iron pan for approximately 20 minutes. oh yeah.