This is my favorite--Gymnocalycium megalothelos from Paraguay. My east back patio provides just the right amount of light shade for it. This one needs to be kept on the dry side in the winter. The flower on the right that just closed was pink, as opposed to the peach colored open bloom. I just purchased these two cactus and will have to find the perfect pot for this one! This hobby is becoming very expensive!
Mammillaria saboae ssp. haudeana is a miniature from Mexico. It takes light shade here in my area. It clumps, and has pale lavender flowers about 1 inch across. It will grow to about 1.5" and about 3/4" wide. If you enlarge the photo you can see some a neat spine arrangement on this tiny cactus. Three more buds are forming right now, and then, once those are spent, that should be it for the season.