Where can I find information about classification for organic foods?

The Organic Center. The generations of organic website, http://www.Generationsoforganic.Org/ , is an information site for families put out by the organic center. I'm on their board of directors and used to be their president.
USDA NOP. Certified organic food is grown according to standards set by the national organic program of the usda. http://www.ams.usda.gov/amsv1.0/nop.