I have an 1880s vintage spoon with a mark I cannot id. It looks
like a standard lion passant from British silver, but there's an
extra item below the lion, like he's standing on a rock with a "K"
on the rock.
I think it's the Sterling mark of the firm of J. B. & S. M. Knowles. "It was founded in 1875 by brothers, Joseph and Stephen Knowles. The company was primarily a manufacturer of flatware, but did make some hollowware. The firm was later purchased by the Mauser Manufacturing Company." This website features the mark at http://www.925-1000.com/american-mfg5.html" onclick="window.open(this.href);return false;.