Called this one "Starry Night" for all I could see were zillions of perfect little stars arrayed in a pleasing pattern. These small cactus are about 3" diameter, all in a sale tray at the Boyce Thompson Arboretum. The horticulturist there names the plants and these had little ID stakes with "Pettable cactus" printed. In the lower right corner you see a peeking pink bloom on another of these cactii in the tray. The ones that had blooms had rings of the scarlet blooms around them.
If you like macros of desert plants, many are coming along. The previous one I like for different reasons, seen here.