You can eat field corn just fine. You shouldn't eat it raw at maturity because of the high starch content, but the solution to that is simply to harvest a bit earlier before all the starch is formed. It's not very sweet, but it's perfectly edible.
There are two primary types of corn: field corn and sweet corn. Only sweet corn can be eaten raw or lightly cooked, but field corn can be turned into edible products (e.g. cereal) with some standard processing.