I feel it is my duty to bring home every good and special old set of blocks I come across, especially those that are singular.  These are smaller in scale than US Embossing Co. color cubes, but follow the same design, with red, white, blue and yellow solid colored sides, and then two sides of diagonal two color combinations. One block here is a substitute, colored red (looks like crayon) on all four sides; I always like finding these sorts of additions, all a part of the ongoing life of a well used set. And the paper label adhered to the slide lid is interesting and unusual, with a masonic compass and square emblem at center, and pattern possibilities  all around. Looks like these belonged to a Mrs. Robinson, whose name is written on the underside of the box.

4" x 4 1/16" x 1 7/16". One substitute block as shown, but otherwise in great shape, hand-painted wooden blocks, well used, in box that is a combination of wooden, jointed at corners, with hardboard top and bottom. I can't find another set like this out there anywhere, c. 1920s-40s I would guess.