This coin may have spent some time in one of the older Kraft 2x2 envelopes. Back in the day, it was common to put square gauze bandages inside to try to keep the coin from contacting the high-sulfur paper. That would explain the squared area without the heavy toning. I know it's debatable whether envelope toning is natural or artificial, but to me it is natural.
As I look at this coin, I think I see light wear on the high spots of the design, most evident on the hair over the ear, cheek, right cotton ball, and cap curl. The reverse looks like light wear on the eagle's breast, left claw, and left wing tip (our visual right). I could be persuaded otherwise here, but I'm leaning toward AU-58.