Found A Couple Of Interesting Coins - Coin 1 1986-D LMC

Thanks, I was more referring to the outside of the monument. In the top-right corner, it almost looks like a groove squished in there, but it goes all the way down the right side (more or less prominent in areas).

Any thoughts on the roll above Lincoln's hair?

Keep in mind they are polishing the dies to remove clash marks and die damage. So when enough of the fields go away, you can see a halo around the outline of the bust/design. We often see this on Kennedy halves:

And Dimes:

These are after many polishings happen and the dies devices get smaller as the fields are being reduced. All these thing are die events. Something that the dies suffer from die abrasion and die wear. They are used until the die is no longer suitable for coinage. During the 1950's the cent dies were used way after normal retirement. So when you look at those years you find a lot of strange events happening those years.

Only keep it if you want to share it will a new collector you will find. I try to show you what I see on your coin. So you might want to start saving images of interest that you can use later in your own educational files.