My circulation "white whale" is the 1999 WAM. I KNOW I should be able to find one, I've found a handful (I mean like 5 of each) of the 1998 and the 2000..... The 1999 WAM eludes me year after year! The Bicentennial quarter S is 40% silver so I'm not crazy about it, lol, but seriously, they made like 11 mil uncirculated S and 4 mil proof S in 40%. it's probably easier to find in circulation than the 1999 WAM, but all 1999 WAMs were released to circulation, while the Bicentennial S quarters were released in a set and have to be broken out to circulation. And a lot likely were melted over the last 45 years also. there has to be an attrition rate to it over the last 4-1/2 decades. It's a good goal, you gotta have goals! hahaha
1999 WAMs are tough, man. I'm closing in on $20,000 worth of cents searched and have found a total of 2. Closing in on almost 100 each of the 98 and 00.
Marks in yellow? Marks in red? I don't see what you are referring to so I must be not getting the photos.
I see this same type of mark on the obverse as well, running from the forehead, down through the temple and upper cheek. I think it could be from some type of chemical that got on the surface of the coin and "ate" away at the material.