What's The Oldest Coin You've Spent Or Put Back Into Circulation?

The problem with your question is over what period of time? For example I am from a time when everyone spent all Silver coins as if they were just coins.

Just to mess with people, I have released into the wild a few 17th Century Lithuania Szelags and Polish Solidi. They are about the same size as thin dimes, but made from copper. I've also given about a dozen away to folks who financially support CCF.

while I quarter roll search and in the beginning I kept all 1965 - 69 till I ended up with just too many.
So I cherry picked the better ones and dumped the less than good ones.

So I did spend a bunch of 1965 quarters (The first clad year)

As a rule, I keep all pre-1959 cents and nickels I find in circulation.

Silver dimes and quarters also stay with me, which means anything younger than 1965 cannot escape my clutches.

So I would have to say the oldest coin I've put back into circulation overall would be 1959.

Anything past 65

Nope - never put any collectible in circulation - just felt if this Wheat cent is worth 2¢ then it should be 2¢ in my hand - LOL!!!!

If it's got a modern design and isn't silver it's getting spent.

I don't use coin change much, but dateless buffs, any Jeffersons, any Lincolns, and any Washingtons post '64 are all fair game.

Never spent a half dollar or dollar coin in my life, that kind of change just isn't really a thing too often

Since 1997 the oldest UK coins in circulation are 1p and 2p coins dated 1971. I spend those without even thinking about it.

I've often disposed of low quality duplicate foreign coins by spending them when I travel abroad. I remember spending a badly scratched 1938 Canadian nickel in Toronto a few years ago, and I've put a couple of dateless Buffalo nickels and a few grotty wheat cents back into circulation on trips to the USA (I didn't know then about Nic-a-Date!)

In my childhood I'm sure I must have spent a few Victorian bronze pennies, but the oldest coin I actually remember spending in the 21st century was a Swiss 10-rappen dated 1895. It was in about Fine condition but scratched on the obverse with an attempted piercing! I handed it over with other change to a waitress when buying a beer in Zurich in 2005 and it was accepted without comment (they are legal tender back to 1879 and the design has remained unchanged since the first year of issue).