A couple years ago (like 3 or four) I was walking around in Home Depot lookin' at the cacti, and I often noticed some pieces of cacti just sitting on the trays. So, I just took a couple and stuffed them in my pockets. One of them has grown a bit, and has made lots of little baby cacti around its base. And just last week, my mom noticed a little flower bud on it. Now, this is a bit strange, because it has been in the same little 2" clay pot with the same soil (not much either), and crammed with another type of cactus for 3 or four whole years. Plus, it has been growing on a north or north-east facing windowsill. So, don't ask me why it's flowering. I'll be sure to get some pics when it's open.