from the whitish corrosion or white rust I would say it is lead. lead that has been in the ground for quite some time. most likely leftover or a spill from pouring bullets or sinkers or maybe even from a plumber's kit. my guess
Good to know! I was confused about the white spots too (thought maybe it was a small amount of concrete or something).
I'm guessing it must be a lead mix based on what most people are saying here and based on the location found (an old logging trail in a heavily deer hunted area). I'll second your thought on it possibly being over spill from pouring bullets.
Thanks for all the help everyone!