"Q. As far as you know, what was the basic evolution of polyhedral dice? If they existed prior to the creation of Dungeons & Dragons, what were they used for?
A. To the best of my knowledge I introduced them to gaming, en masse, with D&D in 1974. I found sets of the five platonic solids for sale in a school supply catalog back in 1972, and of course ordered them, used them in creating the D&D game."
As a connoisseur of 'origins of things which somehow seem to have always been around' I am amused by this.