Already a multi-millionaire in his early thirties, Herbert Hoover became interested in public service. In 1914, he put other men in charge of his mining business and gave all his time to Belgian relief during World War I. In May 1917, President Woodrow Wilson asked Hoover to come to Washington, D.C., to serve as his wartime food administrator, which, once he accepted the position, Hoover insisted on doing without any salary.
As food administrator, Herbert Hoover had absolute control over what American farmers produced, how much they were paid, what and how much produce went to the American army at home and abroad, as well as to the general public, and how much stores could charge customers.
Hope this helps you out!