We have taken
Crisps (Tayto for the irish folk)
Cereal out of its cardboard box (because my sister swears it taste different!!)
Bread, (two or three loaves which are frozen on arrival, becuse my mother says US ones are too sweet)
Tea bags (again cause Mother says its different)
Cadburys Chocs (just for the hell of it)

Once its not meat or dairy products we have not been stopped, we were asked by costoms once if we had food and we said "yea crisps" after a funny look, I said like potatoe chips! not problems!