My 16 year old DS is consistently running late, so he never has time for anything more than a fruit bar. On the rare occasion that he gets up on time, he will have waffles (Eggo Nutrigrain), frozen pancakes, yogurt, cereal, frozen bagel with cream cheese, and sometimes I buy those Jimmy Dean pancake sandwiches (if I have a coupon).
He usually brings some sort of packaged thing to eat in 1st or 2nd block too...I don't buy these every week, but we've tried the oatmeal squares, breakfast cookies, and breakfast to go pouches. He also will take a granola bar, or special K bar...something like that. Or, he eats part of his lunch...the fruit or the veggie. He is long and lean, and he needs to eat small meals more frequently. That is just how his metabolism runs. Thankfully, his teachers this year have been pretty lenient about food in class.