I've done this with many different types and brands of peanut butter and bread, after a few hours (I typically pack them in the morning as a snack for the afternoon) the bread gets rock hard. I'm curious why this happens, but mostly how to keep them from getting hard ?
The bread is never toasted, I just spread the butter. I've tried keeping it in a plastic bag, in the fridge, outside the fridge, wrapped in paper towel...nothing.