You are looking for a small Tupperware container hidden along a path behind the Copper Culture Indian Cemetery 5556 B.C.
At this site about 5000 years ago Wisconsin Indians gathered to bury their dead. Because of their use of copper tools, weapons and ornaments, this group became known as the Old Copper People. This site was excavated and studied in 1952.
Enjoy!
~The Lil Otter
History:
In June of 1952 a thirteen year old boy discovered human bones while digging in an abandoned gravel quarry on the western outskirts of Oconto. Commercial gravel operations during the 1920s disturbed a large area, most likely destroying a considerable portion of the burial site.
Nearly all the burials occurred in pits; both burial pits and cremation pits were found. At least forty-five individuals were excavated in the area worked. The site yielded a total of twenty-six copper artifacts including awls, clasps, spear-points, fishhooks, & a bracelet. In addition, a whistle made from the leg bone of a swan was found, two well-preserved antler tips, a series of snail beads, a fresh-water clam shell (the nearest source being the Mississippi River), and a shoulder of a large lightning shell, a type of whelk whose present distribution is the Atlantic Ocean from North Carolina to Florida. The importance of the last two items indicate trade or contact with a region over a thousand miles away. No pottery was found.
Since that time, the site has been dated to about 5000 years old and additional Copper Culture sites have been found in Wisconsin and Upper Michigan. This burial area, however, appears to be the oldest in North America as of the year 2001. The site was placed on the National Register of Historic Places in 1966. (source Oconto County Historical Society)
Old pictures and info from 1952 see:
http://www.rootsweb.com/~wioconto/CopperCultureCemetery.htm