USDA's website announcing the rule that will take effect for 2014-15 school year
Federal ruling and CHCCS Board policy: Federal regulations prohibit bake sales held before 30 minutes after the official end of the school day. In the event that a sale occurs prior to 30 minutes after the official end of the school day, all proceeds must be turned over to the Child Nutrition department.
USDA’s “All Foods Sold in Schools” Standards

Smart Snacks in School Infographic