California here

. We aren't allowed to bring homemade treats, either. California passed the law about two years ago, right before my oldest started kindergarten. While I'm sure allergies factor into it, my understanding about the reasoning behind the law (in our state, anyway) is that a professional kitchen will ensure healthy handling of all foods. We can still bring cupcakes, they just need to be bought from a local grocery store or bakery. It's really sad.

Now, if I want to bring in a healthy treat for my DD's birthday, I have to spend an arm and a leg at Whole Foods. They are really encouraging non-food items for celebrating altogether, however, and if you do bring a store-bought treat it has to be given to them outside of the classroom at the end of the school day.
CA here too, and our school must have missed the no foods from home kitchens rule, that or they just choose to look the other way.
They're being strict about district "wellness guidelines" though:
Birthday celebrations are discouraged. If you really want to do something for your childs' b-day, no food of any kind is allowed.
Food cannot be used as a reward or incentive.
Only 3 classroom parties a year, and only 1 treat is allowed at each party that does not meet standards.
Any food served at school wide events must meet standards.
Wellness Standards:
Food
�� Not more than 30% fat
�� Not more than 10% saturated fat
�� Not more than 35% sugar
�� Not more than 175 calories per item
Beverages
�� Fruit-based drinks, no less than 50% fruit juice and no added sweetener
�� Vegetable-based drinks, no less than 50% vegetable juice and no added sweetener
�� Drinking water, no added sweetener
�� 2% fat milk, 1% fat milk, non fat milk, soy milk, rice milk, etc.
Honestly it's easier to just buy uber expensive, individually wrapped 100 calorie packs and call it good.