W. W. Denslow broke into full color endpaper designs with his own books. For Denslow's Mother Goose in 1901, the design is reminiscent of Dot & Tot of Merryland. Both books were published in the same year, but this time, rather than a parading toy band, we have a repeating design of geese.
In Denslow's Night Before Christmas, published the following year, the endpaper design bursts across the page in full color with an array of toys, Santa, and a Christmas tree that only Denslow could have come up with!
Of the three remaining full length children's novels illustrated by Denslow, only The Pearl and the Pumpkin from 1904 has pictorial endpapers. Here the design covers both pages but is printed in a single color, turquoise. The endpapers are also seen in two colors, orange and black, in what are generally thought of as later printings of the book, although priority is uncertain. Billy Bounce and The Jeweled Toad both have plain endpapers, which is too bad - I'd like to see what Denslow could have come up with to welcome readers into these stories.