I'm trying to figure out what's going on in the reverse field of this nickel. These pics are of the most pronounced area, but its all over both sides. Is it a die that is just worn bad, needs polished? The devices seem strong enough. Is it a rusty die? My understanding on rusty dies is that it was more common on the 19th century coins. Is it a planchet issue? I've poured over error-ref.com's planchet errors but since I don't know what to call it, I've not really found anything that matches.
