Here you will find a patch of land with a stone monument explaining the treaty line road. The cache will be a small capsule, if the glue holds it will be camouflaged.
The land lying south of the boundary road, in Jay County, was ceded to the United States by the Indians in a Treaty made at Greenville, Ohio, August 3, 1795. The line began at the mouth of the Cuyahoga River, and, after various windings, reached Fort Recovery, and proceeded " southwesterly in a direct line to the Ohio River, so as to intercept it opposite the mouth of the Kentucky or Cuttawa River."
This treaty was signed, on the part of the United States, by Major General Anthony Wayne, and by the Indians, by the chiefs of the following tribes: "Wyandots, Shawnees, Ottawas, Chippewas, Pottawatomies, Miamis, Eel Rivers, Weas, Kickapoos, Piankeshaws and Kaskaskias.
More info can be found at : http://genealogytrails.com/ind/jay/history5.html
P.S. It will sometimes disappear do to rain or upkeep of the small yard. An uploaded picture will work as well as a signed paper if you cant find it. The idea for this one is to see the monument as much as finding the cache.