Is the destination Ireland as someone mentioned? Go to www.citizensinformation.ie and look up restrictions. You should be OK to bring in snack foods that are dry, but don't try for those small milk boxes (like a juice box but with milk) -- Ireland does not permit anyone to bring in any dairy or meat products even for personal consumption. (No jerky....!)
Otherwise, I'd say you're fine, but to be safe, bring things in their original U.S. packaging in case customs in Ireland gets curious. I would take three suitcases instead of two and spread clothes and snacks out among the suitcases so you don't have one suitcase loaded up with food; that could get it opened and inspected because they may want to know if you plan to resell it (I know you won't but they have to ask if they see a lot of foodstuffs coming in--they would not stop you but might be obliged to check the bag). Then you have one empty suitcase at the end of your stay and can pack that with whatever souvenirs you buy or are given.
We go to England each year and though I'm not sure if Ireland is more or less expensive for Americans (current rate now is one British pound to $1.70 so it's lousy for us), I do find a lot of very inexpensive snacks there, many costing less than in the U.S. (crackers, graham crackers, snack bars, dried fruit packets etc.).
I'm sorry some folks didn't answer the question directly but the original post didn't say you were going overseas.