My most memorable site that fits that description, was this:
In the early 1990s, I researched out and found a country picnic site, that had served a small town of only 700-ish people. It was a country meadow where all the townsfolk would hitch up their wagons or model T's, each Mother's day, easter, 4th of July, etc... and everyone in this little community would go out and have a picnic a few x per year. The town was small, and the years of usage were fairly slim (some usage in the 1880s, and again in the 1910s/20s). The last of the picnics in this oak grove ended in the mid 1920s, d/t a new park came into vogue elsewhere. So after the mid 1920s, it's just been nothing but a cow pasture.
Thus it was a) strictly picnics, b) pre-dated foil and tabs and aluminum, c) never had any structures or buildings there (that introduce building material junk, nails, etc...).
The place was a dream come true. The only "junk" we had to deal with, was occasional bullet shells, shotgun butts, etc.... We ended up pulling about 150 coins, from seateds, to early mercs and wheaties. I think the absolute newest coin we found was a mid 1920s mercury dime.
