The pictures are really bad. In reality it looks really quite good (to someone who doesn’t know what he is looking at). There are two spots on the head of the coin that look like corrosion. Under a magnifying glass it looks like the corrosion is on the surface since I can see all of the details intact beneath the corrosion. The rest of the coin looks like plain old light green/brown tarnish. The rear of the coin appears to have no "corrosion". Most of what is showing up in the pictures as corrosion - appears to me to be a copperish color - there is no perceivable dip in the surface.
i would try the water thing. that is a nice coin! i agree, before you cut your grass again, run over it with a metal detector. if there is 1 old coin, there might be more. how did you find it? was it sitting on top? thats a really nice coin and i would say its worth $10-$15 in that condition. nice price for a nickel!:kewl: