In our guild, it's called "Lotto Block" and we usually make two blocks every other month. One month is "giveout" month, the next month you bring both blocks back and they're put in a drawing for all the blocks. You are allowed to keep the instructions if you wish to make a block for yourself from your stash. In the kits we're given, they provide 1 or 2 fabrics and you come up with the rest from your stash.
So far, I haven't won any, but it was a lot of fun making them, and a learning experience!