Michael Pollan, Omnivore’s dilemma (2006)
A good read about food in general. The first chapter describes the prevalence of and dependence on corn in the food industry in the USA. Pollan also explains how hybrid corn is grown and processed.
Margaret Visser, Much depends on dinner (1986)
An entertaining food history book, though some parts of it are a bit dated by now. Chapter one gives some of the back story about how corn became such an important food crop in North America, starting with various native peoples who first cultivated it.
King Corn is about how corn products are practically everywhere in American foods. (The movie is low on insight — especially from a corn allergy perspective — but it has lots of scary shots of corn).