Books. My wife and I must have thousands of books. Fiction and all kinds of non-fiction, on all kinds of topics.
And like Zenster, we also like cigar boxes, although we don’t have quite as many. But we’ve got some nice antique ones, as well as the run-of-the-mill ones.
I used to collect cigarettes–packages of all kinds of different brands of cigarettes from all over the world. I had hundreds, sealed in their original cellophane and with their tax stamps and so on intact. Damaged them in a move some years ago though, and lost interest afterwards.
Does one of anything constitute a collection, if it’s big and you plan to collect more when you get the room for them? I’ve been a fan of pinball machines for years, and have owned a beautiful old Gottlieb electromechanical from the mid-1970s for quite some time. (Fixed it up so it is playable, too.) But I’d like to have more of the 1970s electromechanicals, and plan to look into getting more (if possible) when we can manage to move to a bigger home.