Don Lutes, Jr., of Pittsfield, Mass., found a rare 1943 Lincoln penny in his change from his high school lunch back then.
He'd held on to it ever since, until he died in September.
The 1943 penny is special because less than 20 of them were ever made and they only exist due to an error.
In 1943, pennies were supposed to be made of steel because copper was needed for other uses during World War II. But a handful of the coins were mistakenly pressed with copper, like the one Lutes discovered.
The pennies are so rare, the U.S. government denied they ever existed.
Lute's rare coin is now up for auction, which is slated to end Thursday.
A similar penny sold for $1.7 million in 2010.