See also: Philately
A couple weeks ago, a friend asked me if I'd like a coin collection that had fallen into her possession. Sure! So we had a short, socially-distanced meeting and exchange. The collection turned out to be contained entirely in a standard-sized ziplock bag, and the most unusual thing about it was that it contained a selection of much smaller ziplock bags, each containing a scrap of paper with a country name and a small number of coins. But there were also a couple well folded bills, and these were intriguing to me:
photo: Bank of Biafra 1 pound note
I had no damn idea where or what the country of Biafra was. And that was an education. I mean that in the most literal sense: receiving this bill led me to learn a great deal about the geography and history of Biafra. It existed from 1967 to 1970. And if the name "Jello Biafra" means anything to you (the lead singer of the Dead Kennedys), yes, he did name himself after the country. Here's the Wikipedia article on Biafra. It was part of the still ongoing racial conflicts in what is now the country of Nigeria.
Setting aside the fascinating and horrifying politics, you'd think the country's incredibly short existence would make this bill relatively rare. You'd be wrong: it's worth a few cents.
This is the other bill:
photo: 1947 Italian 1000 Lira note
I thought that Italy had raging inflation after the Second World War, and concluded that this was a very small bill. I was wrong. A bit of research eventually showed that in 1947 when this was printed, the Italian Lira was pegged to the U.S. dollar - and that this bill had the buying power of a modern (2021) US $20 bill. Not a huge bill, but large enough to be relatively uncommon among collectors. Even in its somewhat damaged state, this one appears to be worth about the same as its old buying power: about $20 US.
I get that most people see coins and bills as nothing more than desirable markers of wealth, a tool. But if you take the time to look, they're an education about the symbols of the country - and later, its history.