Today's plant is another Mammillaria cactus, possibly Mammillaria polythele. It didn't come with a label, but I think that's what it is. That species is widespread across central Mexico.
It has typical Mammillaria flowers, small and pink. The body of the plant has prominent angled tubercules that give it an interesting appearance.
I like the way the spines look like stars. The spines are also very stiff, and this one is quite pokey!