i have premade baggies of cereal ready and they can take along a cup of milk to drink with it.
Also, my kids have been eating frozen waffles since they were babies and it is a standard on the run breakfast for us. They like them frozen still (not cooked, just frozen) Their faves are cinnamon and blueberry.
string cheese, yogurt, yogurt smoothies are all great options too.
Fruit slices can be taken with these.