check out "sofie safe cooking" on amazon. It's pretty good. I've also had great luck with vegan cookbooks - I particularly The Joy of Vegan Baking.
The best thing to do to adjust to eating with allergies is to change your mindset about 2 things:
- the majority of foods you eat need to be whole foods. There are tons of things your son can eat - fruits, veggies, hummus, pita bread, ritz, graham crackers, bagels, dry cereal, oatmeal, some granola bars, fruit snacks, chicken, hamburgers, etc, etc etc. The thing is - most of them will be whole foods, not prepared foods.
- you need to cook from scratch. You aren't going to find muffins or doughnuts or read to eat stuff that he can eat unless you drive to a specialty store and even then it's going to be really expensive. If you cook everything yourself then you should be able to adapt.
Oh last tip - my boys are calling - check Amazon's grocery section, when I first started out I bought snack stuff from there by the case cause I could get it shipped to me.