Prior to inventing Corn Flakes, one of the oldest cereals still on the market, fellow health nut John Harvey Kellogg was inspired by James Caleb Jackson's Granula and began making his own version.

Not far behind was Bran Flakes, another one of the oldest cereals you can still find on supermarket shelves, which launched in 1915. In terms of snacks, Cheez-Its are the snack that's been around ...