Here's a little item I'd forgotten all about: my collection of postal error labels.
I used to work with a non-profit that received a lot of mail and, necessarily, sent out a lot more. We were a non-profit, we had to contact old donors, new donors, potential donors, etc. One of my roles at this place was to update donor records with new address information, when applicable. Sometimes that meant nothing more than noting "old address canceled, no forwarding address" and putting a hold on the record.
But I was intrigued that we received so many donations from around the world, and not all of our distributed mail reached its destination. It was inevitable that mail would be returned to us--not for improper postage, but for all sorts of reasons: no forwarding address, misunderstanding in the address, bad weather, processing error, force majeure, what have you.
I saved them up. Sometimes they were labels I could peel off with care, sometimes they were stamps I clipped with scissors. I collected them all out of curiosity, just to see how many different kinds I could get. Notice the details of the pointing hands, how they're essentially the same but with slight differences.
Eh. I thought it was neat.