Here's another stock cover used by the publishers Donohue & Henneberry for a variety of titles. This cover intrigues me, as it it looks like it could be a W. W. Denslow design - but there's no definite indication. The design uses several common elements seen on Denslow covers - in particular, the band of color across the top and the repetition of a design element, laurel wreaths in this case. This cover was also produced in at least one other color combination. The image isn't signed, and there are aspects that don't look like Denslow to me - but it's fun to speculate and theorize!
This cover was used by Laird & Lee for a set of works by Opie Read. Here again, there are elements that make me think of Denslow, but there's nothing to firmly indicate that this is his work - and it does look a lot like many other stock book covers from the time. Denslow did do work for Laird & Lee, and this particular title has a halftone frontispiece by him - apparently earlier printings contained 4 plates.
Part of the fun of collecting is keeping an eye out for possibilities - these may both be wrong, but they are intriguing!