M.H.
I just wanted to throw out one more suggestion... Check with the school to make sure it is okay to have peanut butter. I sent a pbj with my son on his first day of MDO and found out a week later that the school has a "no peanut butter" rule, even though there aren't any allergies in his class. He's a very picky eater so I was disappointed that one of the foods he will eat wasn't allowed!
He gets to school at 9 and they eat around 11:30, so keeping food cold isn't that big of a problem. I also use an ice pack that others recommended, or else he just eats things like apple sauce, mac and cheese, cheese crackers, fruit, etc. at room temp. Good luck!