Primitive charcoal or folk art?

This has been in a trunk in my grandparents/ then my parent's house. It appears to be charcoal. I believe, while the frame is beaten up, that it's original. The glass appears to be original as well because of the numerous flaws and waves in it's structure. I'm a complete novice, but thought this might be either folk art or a primitive. No signature, but on the back there are instructions on it's design. Any ideas on what it is and/or what it might be worth? Any help would be greatly appreciated!

Poor