Debated. Eleven unused stone blades were found, but their date and their link to the Adena people are not sure.
They lay under disturbed ground at a golf course in Sugarcreek, Ohio. Each blade is leaf-shaped, with flakes struck off both sides, and none shows wear from cutting or hunting. Charcoal under the tools gave dates from the middle of the 1100s to the middle of the 1200s AD. The page warns that machines had already scraped the ground, so those dates may not be safe. By shape, the blades sit closest to Adena tools from about 1,900 to 2,500 years ago. Most of the stone came from about 43 to 45 kilometres away.
The page says no one knows why these unused blades were buried.
https://www.ancient-origins.net/news-history-archaeology/adena-stone-tool-cache-00102852