I think your coin has environmental damage which has discolored it. The edge should tell you if it is a missing clad layer or not. It will also be thinner and weigh less.
Environmental toning. Missing clad layer usually just occurs on one side. Here are coins exposed to soil, dirt, sand, water and/or chemicals for long periods of time.. I found them detecting Even Nickels.
I opined the OP coin might have been in the ground based on the fairly even toning on both obverse and reverse and the solid contaminants left at the M on the reverse. Also from the stain continuing to the F of Of. I guess I’m missing the correlation that light circulation precludes any type of environmental toning. Don’t take me wrong, I’m wrong All the time! Just ask my wife.
To me it just doesn't look like a metal detector find. I have seen the striated look on many modern denominations. More so on coins that have never seen circulation. The toning none the less looks unnatural, and is difficult to tell what happened. It is anyones best guess as to why it looks like it does, and I surely don't know everything.
Lots of potential causes, but since we weren't there when the surfaces were environmentally damaged, we don't know the exact cause. It doesn't matter, really, as the coin's surfaces look like that after the coin was minted and released into circulation.
The quarter in the first post? If so, I agree that it's not too circulated (mid AU?) and doesn't look like it came out of the ground. It could be a number of causes. Regardless of the case, environmental damage would be the "designation" I'd give it. I'd also add, it looks a lot more attractive than what one would find in the ground. The obverse also vaguely reminds me of woody cents.