New Forest Stone Age nutshell 'reveals prehistoric campsite'
They were discovered along with a monument and five urns from the Bronze Age during two digs at Beaulieu Estate.
Archaeologists working on the New Forest National Park Authority (NPA) project said evidence from the Mesolithic period was rare.
They might show there was a prehistoric campsite in the area, they added.
NPA said the "charred remains" of the hazelnut shell were given a "surprisingly confident" Mesolithic date of 5736 - 5643 BC by radiocarbon dating.
"Archaeological evidence from the Mesolithic period is rare but now and again we do find flint tools and evidence for these temporary settlement sites," said Jon Milward, of Bournemouth University Archaeological Research Consultancy.
"We know of a few Mesolithic sites close to Beaulieu River and it appears there was another at this site."
The NPA said the investigation of the ring ditch monument had "added significantly to our knowledge of prehistoric activity in the New Forest". ■