OK Guys, this one is kind of a mystery to me so i'll leave it up to debate. I have a 1918 Lincoln Cent in which the obverse looks somewhat convex while the reverse looks concave. The rim is intact on the front but is completely smooth on the back. Mint Error or Post Mint Damage?
It could of been mounted on a bezel. Or made into a piece of jewelry like onto a bracelet then taken off. I say PMD. IMHO
Welcome to CT. I've seen and even made coin jewelry and it doesn't appear as "dished" as many are to make into something, but @paddyman98 could be correct. Some better, Full Image photos might help. Here what I usually send to new members. You should always post in focus FULL IMAGE photos (after you upload your photo, two buttons appear: Thumbnail and Full Image, click Full Image and your photo appears full size on your post and is easily enlarged by clicking on it). Photograph coins on neutral backgrounds like black, grey, or white. Crop out superfluous background so just the coin shows, and post photos with correct orientation so members don't have to turn their computer in some awkward fashion to view it properly. While it isn’t always necessary, it is nice to show both the obverse and reverse, even if your question is just about one side. Members can often give more valuable information having both sides to evaluate. Add close ups of areas you have questions about and make your questions as definitive as possible so we know what you are asking for. And try to have the best lighting possible to show the most favorable photo of the coin. Hope this helps in the future. Good luck.