We cannot give you a full list of food, but anything that was feasibly present in ancient Japan (so, before international trade became a big thing) plus anything that can be produced by Hisui pokemon is fair game.

So, for example, Rice is fine cause that was present in ancient Japan. Eggs are fine, because you have pokemon like Chansey that produce eggs, but milk would not be there because there are no milk-producing pokemon (such as Miltank) on the Hisui pokedex.