Nowadays there's a collection system for these scraps of wood produced by large woodworking factories, and they're some of the few waste products from human production which are recycled, normally into new boards. Still, I think it's a good idea to give these materials a second chance as far as possible.
If you want to know more about the materials most often used by large carpentry factories, check out this article:
Today, for example, I collected these pieces of sucupira, teak, bubinga and sapele from a carpentry factory's waste skip. As you can see, some of these pieces are of a considerable size:
Wooden base for my dowel plate made with those bubinga pieces:
