Harmonica reed, Date anywhere from civil war period to 1950's. Seems they're all the same
Ok, I agree, not a book. The bottom corners are too rounded, but I'd otherwise thought it had the curvature of an open book.
Do you suppose there's any use in trying the flour trick, sprinkling it on and wiping it off, sometimes revealing a bit more detail (on the shield hopefully)? Or a pencil rubbing?