That's A Lot Of Inflation

Remember the first Presidential $1 coins that had edge lettering?  Remember the brouhaha after a few were found without the edge lettering?  Mistakes sometimes happen in our US mint facilities, and sometimes those errors are released to the public.  A big error happened during WW2:

A penny that a Massachusetts teenager found in his change from lunch money could be worth as much as $1.65 million (£1.3 million) when it is auctioned off.

The 1943 Lincoln penny is made up of copper and has been described as the "most famous" coin made in error, according to Heritage Auctions, which is auctioning off the coin. Only 20 were ever made and for years the U.S. government denied its existence, but one coin was found by Don Lutes Jr. in his school cafeteria in March 1947...

In the 1940s, copper was considered a strategic metal, largely because of World War II, as it was used to make shell casings, telephone wire and other wartime necessities. To preserve the metal, 1943 Lincoln pennies were made of zinc-coated steel, but a tiny fraction of the pennies put into circulation wound up using copper.

The 1943 pennies are gray-colored "steel cents".  This kid's cent is made of copper.