Many, many years ago I had a Whites detector. After searching fields, pastures, and other flat areas, and after finding bottle-cap after bottle-cap, I almost gave up. However, I sat down to think about where, exactly, "old coins" might be found?
The idea I came up with was to search the library and local Historical Society for references to locations where there were old amusement parks, and fairgrounds. Think 1800's to early 1900's. It took some sleuthing, but I found several. On visiting the sites, I tried to imagine how the fairground was laid out. In some cases there were structures still in place. Decrepit and rotting, but, still there.
I found many coins, bracelets, rings, etc. These finds sure beat the bottle-caps in the fields!!! I also found one amusement park that still had the infrastructure for a very old roller coaster. Big thick trees and shrubbage growing up and over the top of it. The ticket booth (or at least I assumed it was the ticket booth) was right across from an old gate leaning in on the entrance to the roller coaster. I scanned around the area and inside the rotting ticket booth and found lots of silver!!!
If I were still doing this, I would probably start again with the library and Historical Society to gather intel. I would try to think of any venue where old time coinage was exchanged, and then focus my efforts on those areas. Amusement parks and fairgrounds "way back then" exchanged coinage for the right to take the ride. Wherever coinage is exchanged, you stand a great chance of picking up what someone else dropped...........