My general philosophy is to buy things whose sheer existence makes me happy, which is certainly the case with this, surely once the side of a trunk, iron handle still in place, and which someone cared enough to salvage. The red breasted yellow bird on branch of what looks a bit like bleeding hearts gives me all the pleasure of a fraktur watercolor, with the wavy yellow border and then dovetailed edges of the panel making the perfect frame! Plus that best blue ground and a built-in knocker! 

17" x 14 1/2" x 7/8" thick, super solid and sturdy and wonderfully worn. The handle flips up and down smoothly, but really doesn't make enough to serve as an effective door knocker! Mid 19th century or so I would think. Strung with twine on the backs for hanging, which works fine.