This is one of my prettiest cacti, I think. This is Mammillaria theresae, native to central Mexico, and is another that is critically endangered in the wild.
The flowers are a lovely shade of lavender, and are so delicate.
The spines are plumose, feathery, very soft and pretty.
The flowers last a couple days, and while there's no scent that I can detect, the display more than makes up for that lack.