Yeah that will do. Vegetable peelings, fruit, apple cores grass, leaves, even tort poop. You want things that decompose quickly. I personally would put paper in too, just to be safe don't put paper in with ink on it. But everything up smallish. Don't put any sticks/branches, they take years to decompose. Make sure you have a lid on it too. Just a piece of wood thrown on will do.What about 30cm? What type of organic materials should I add in?