My father has a collection of hammers, scrappers, points, awls and knives (mostly knapped but some merely shaped). He or a family member found all but a couple pieces.
His most prized piece is a copper knife he found in a road cut in WI. A local museum told him it was native copper, had never been used or sharpened and was 3000+ years old. The tang is very slim and tapers toward the end, which curls back toward the blade, almost forming a circle. Probably not a working knife was the thought, the tang was not made for a handle (or it was still in production).
The museum would not value the knife, they would only say that it was in the best condition they had ever seen, 'museum quality', and priceless.
Steve-O