I have a collection of about 150 cacti. At this time of the year, they start to display their wonderful flowers. Here's a baby cactus, no more than a few years old, I should think, and it has made a sterling effort to produce a flower that is bigger than itself. The cactus is just 5 cm in diameter. As is often the case with cacti, it is difficult to know exactly what sort of cactus it is.
I have numerous books and spend hours searching through them, trying to identify my cacti, but with very little success. The closest I have got with this one is that it is perhaps a Parodia, but that's very iffy.
I have two larger plants of the same cactus, both about 12.5 cm in diameter and both of which have already flowered magnificently, as can be seen in the photo of one of them below, taken a couple of weeks ago.