I'd love it if there was a way to tell wether or not something is edible. I don't want to spend sp, quest points, blue building points, or whatever kind of points on something that I think is edible but actually isn't...

SubetaLodge has a list of all the food. If you make an account there you can make a checklist of what foods your pet(s) have eaten.

Usually it's obvious when something is edible or not. If you're really not sure, look the item up on SubetaLodge. Unless it's a VERY recently released item, all the info on it will be there. :)