There are quite a few rarities in the Lincoln cent series. The latest I read about was the report of a small date 1982 copper cent. All the small date cents were suppose to be copper plated zinc. When the mint was striking the 1982 cents, they switched from copper to copper plated zinc, but they ended up having issues with the older dies, so they made new ones with a slightly different font type. If you do a google search for 1982 small date copper cent you should be able to find the article. I would post a link but was not sure if it would be allowed.
Another cool find that went for I think $100k was a 1969-S doubled die cent.
There are a couple of different ways to get doubling. The most valuable way is if the die used to mint the cents is doubled, like in the 1955 and 1969 cents, plus others too. Then every cent made with that die is doubled. Machine doubling is when the coin is not ejected and is stamped twice and not worth a whole lot. Some scammers years ago would try to sell the machine double coins as doubled die coins.
In sorting copper from zinc cents, be on the lookout for cents that are 1983 and newer, but possibly minted using the older copper blanks. I have seen some pictures online of some of those errors. Apparently some older blanks were run through the process and got out in the wild.
Just keep an eye out for any cent that does not look right and do some research on it, or post pics here and the rest of us can tell you what we know.
Good Luck