There is nothing unusual about this quarter than cannot be explained by the almost infinite number of variables the surface of a coin can come into contact with and be changed by.Toning from circulation is common.
Weight tolerances are 5.443 to 5.897 so the weight is normal.
Some extra help:
If you want to catch a rainbow trout, you need to know what a rainbow trout is.
The same with coins.Save Yourself time, effort, and disappointment...don't learn the coin hobby backwards.
Looking for random anomalies on coins and hoping they match up to something collectable will take you a lot more time, wasted effort, and disappointment repeatedly finding out you have nothing but post mint damage or useless Machine Doubling
, Die Deterioration
Spend some initial time at places like error-ref.com, doubleddie.com, varietyvista.com, conecaonline.org, coppercoins.com etc. to find what actual and collectable coin errors look like.
A good way to start is, for instance, separate a bunch of pennies by date. Go to varietyvista.com and, date by date, use the reference there to see what errors are known for that specific coin/mint mark. Look for those specific errors/varieties using the pictures provided. After doing this for awhile you will KNOW what an actual error looks like and not have to waste time on face value and damaged coins.