I found this penny with errors on both sides and really am not sure what kind of errors they are any help would be appreciated
The one side that has lincoln on is called grease filled die and is common and does not make a premium on the coin, The back side has some foreign substance wich is not a error and is a PMD or post mint damage.
i know it kind of looks like that but with my magnifying glass it really looks like it came from the mint like that