I have friends who collect really interesting things like old maps, and antique photos of kids with toys--really nice things. But I'm not much of a collector except of random materials I imagine I'll have a use for.

I mentally collect though, if that counts. I used to collect metaphorical phrases that were turned in on themselves, like when my wife worried about running a bath during a storm, and I said the odds were like being struck by lightning. Or when I went to a circus, and it was like a circus. Or when re-learning to ride a bike--it's just like riding a bicycle, etc. I remember it began at work when I sorted out a tangle of extension cords and found that one was complexly plugged back into itself, like a snake biting its tail, (or, like an extension cord plugged into itself.) And I thought it made a good metaphor for something, but couldn't think of what. Then I thought it was a metaphor for itself... and it slowly dawned on me that it was more precisely a meta-metaphor for something, including itself, being a metaphor for itself.

And I collect personal stories from people which they won't tell to other people, but for some reason, they trust me with. It's a nice gift to have.