Breakfast cereal wasn't invented until the mid 1900s by a man named Kellogg. He used it to feed mental patients.
EDIT: i just looked it up and Kellogg invented corn flakes in 1907
or before that according to wiki
19th centuryReady-to-eat breakfast cereals have their beginnings in the
vegetarian movement in the last quarter of the nineteenth century, which influenced members of the
Seventh-day Adventist Church in the United States.
[4] The first packaged breakfast cereal,[
citation needed]
Granula (named after
granules) was invented in the
United States in 1863 by
James Caleb Jackson,[
citation needed] operator of the Jackson Sanitorium in
Dansville,
New York, and a staunch vegetarian. The cereal never became popular; it was far too inconvenient, as the heavy bran nuggets needed soaking overnight before they were tender enough to eat.
Ferdinand Schumacher, president of the
American Cereal Company, created a cereal made from oats; manufacturing took place in
Akron, Ohio.
[5] Separately, George H. Hoyt created
Wheatena circa 1879, during an era when retailers would typically buy cereal (the most popular being cracked
wheat,
oatmeal, and
cerealine) in barrel lots, and scoop it out to sell by the pound to customers. Hoyt, who'd found a distinctive process of preparing wheat for cereal, sold his cereal in boxes, offering consumers a sanitary appeal.
[6][7]
Breakfast cereals, packaged, became considerably more convenient, and, combined with clever marketing, they caught on. In 1877,
John Harvey Kellogg, operator of the
Battle Creek Sanitarium in
Battle Creek, Michigan, invented a biscuit made of ground-up
wheat,
oat, and
cornmeal for his patients suffering from bowel problems. The product was initially also named "Granula", but changed to "Granola" after a lawsuit. His most famous contribution, however, was an accident. After leaving a batch of boiled wheat soaking overnight and rolling it out, Kellogg had created wheat flakes. His brother
Will Keith Kellogg later invented
corn flakes from a similar method, bought out his brother's share in their business, and went on to found the Kellogg Company in 1906. With his shrewd marketing and advertising, Kellogg's sold their one millionth case after three years.[
citation 
