Harry Stine, Iowa
$3.8 billion in the agriculture industry isn't too bad. Stine is the son of a farmer and is now a CEO of Stine Seed Co, which licenses corn and soybean genetics. He was always fascinated with the process of seeds and planting and worked in his father's soybean cleaning business when he was young.
Charles Koch, Kansas
The $42 billion chairman of Koch Industries owes that wealth to Dixie cups. The conglomerate makes everything from Brawny paper towels to fertilizers to Dixie cups. His father, Fred Koch, founded the business in 1940, and Charles took over in 1967.