I'm not an expert with coins but back around 2010 I was with some people detecting when someone found a "Horse Head Copper". From that another person told us he had hunted the Ground in NJ where the mint stood that minted those and it was about a 40 minute drive from where we live. Not a week later three of us went there and spent a few hours in a field, stream and park all within 100 yards of where the building was. One of the other two hunters finally found one! It was one of the top 5 hunts I've ever went on because of the research and time put into the planning, and targeting one specific item(Horse Head Copper) and actually finding one.
That place looks the same now as it did in 2010 and its not hard to find on the computer if anyone wanted to try it. Good luck.