on collections

In the The Happiness Project the author, Gretchen Rubin, starts a collection. As she says,
"A collection provides a mission, a reason to visit new places, the excitement of the case, a field of expertise (no matter how trivial), and often, a bond with other people." 
So I'm curious. What do you collect? 

I've started a small collection of Clare Vivier handbags. They are so beautifully made, unique, and the perfect size for day or night. I also collect bottle openers (the weirder the better) and matches from restaurants we visit. Mike collects golf balls from every course he plays.