We didn't use many snack credits in the parks and instead bought stuff in the gift shop as small edible souvies. I was allowed to purchase any food item that was $4.00 or less. I came home with a big bag of bundled lollipops, peanut brittle, shortbread cookies, peppermint tins, etc.
I don't have specific info about bagels and such. The link bicker provided is good info.