A couple days ago, in the comments on the Mother Goose plates I pictured, there was a question about a series of postcards for Kindergarten Shoes. I had never heard of these cards, but did some searching on the web and turned up an image of one (shown at right) - it's very interesting.
This is clearly based on the W. W. Denslow image from Mother Goose, but I don't think it is a Denslow card. There is a signature of F. F. beneath the verse, which I would assume is the artist's signature. Also, the drawing just doesn't show quite the same level of skill as the Denslow. My personal thought is that if a card was going to be issued, it would use the same image as the book - of course, I could be completely wrong!
I was glad to have these cards pointed out - it's always fun to see something new. This does help to reinforce how popular Denslow's work was at the time - he spawned many imitators.
Denslow did do a number of postcards - I only have one, which I've pictured, from his Thanksgiving Humor series.