My mother's husband, Don, had amassed a modest coin collection by the time he died. I and my husband were in the process of trying to determine valuation of the coins (mostly melt value) when we opened a box containing silver coins from the former half of the 20th c, a handful of 'silver' dollars and 4 small jars each full of wheat pennies. We asked my mom about the penny jars (as in why did Don have them) and she said that they had actually belonged to Don's father.
We didn't think we had any earth-shatteringly rare pennies among the collection, but decided to hop on the internet to see what rarities might be out there in the US penny world. Using the search term 'valuable pennies' actually yielded an interesting result. We had known that during WWII, copper was commandeered for the making of munitions. Thus pennies minted in 1943 were made of steel. These steel pennies are not rare, but they are magnetic, so that's kind of fun. If one has a copper penny minted in 1943, well that was an anomaly, and it could be worth thousands of dollars, or so says Mr. Internet. Finding such a penny would be like finding a needle in a haystack, but we decided to check the mint mark and year on EACH one nonetheless. We did not strike gold, or rather copper--no surprise--but we did find about ten steel '43 pennies amongst the haul. Two were an interesting copper-like color and that had us thrown for a minute. Did we actually have something valuable on our hands? No. There were steel pennies minted in '43 that were then altered by forgers to appear as if they were copper, so I suppose that's what we might have. They are magnetic, so that's the tell-tale sign regardless of the pennies' appearance.