DH carries a back pack so we take a fair amount of snacks with us. We pack one of those cheap plastic pencil boxes that you can get at
walmart right now for like 50 cents, the bigger one not the narrow one. We pack it with peanut butter cheese crackers, granola bars, crystal light packets and sometimes pop tarts. And we take a some sort of nuts with us since the protein fills us up. Emerald brand is great to take because thier containers are plastic and they have a decent varienty.
We like the pencil box because it keeps everything together and from getting broken, plus as we empty it we can fill it back up with the cookies or peanut butter and jelly sandwiches that our younger DS doesn't eat at our meals. Then a half an hour after we eat when he suddenly decides that he does want to eat we can give him those.