Depends on the type, some food receives no subsidy. Meat tends to receive a huge subsidys.
2013 Farm Subsidy Database is above. Almost every crop is subsidized in one way or another.
There was a great corn documentary a while ago where a small processor kept making larger larger grain silo's for a while as productivity increased. Until, they simply gave up they now just have a huge pile with a tarp over it. http://www.imdb.com/title/tt1112115/