Like many of you, I've been doing it for years, although on a very small scale. My paper collection includes old two-dollar bills, silver certificates, etc. On the other hand, I have lots of old coins: silver dollars, fifty-cent pieces, etc. I also hoard wheat pennies (why, I don't know), as well as any nickels, dimes, etc. older than 1970, especially those with significant dates on them, like 1944, 1959 (the year I as born), etc.
When I worked on the west side of Cleveland, I used to make a daily stop at a mom-and-pop convenient store (not unlike the one owned by Apu on The Simpsons. I used to get some really old coins there as change, including a penny from the 1800s. It was as if someone just spent their whole vintage coin collection to buy a bag of Cheese Doodles.
But alas! As we slowly transition to a cashless society, one of the drawbacks is that we will gradually lose that occasional thrill of encountering an old coin or wrinkled, faded bill.
That is, unless you happen to spend a lot of time poking around old records in the archives of Lorain County (like author and longtime blog contributor Don Hilton). Then you might get lucky, like Chief Deputy John Hritsko at the Probate Court office in Elyria, as told in the story below that appeared in the Lorain Journal on April 7, 1955.