EASTHAM — Joseph Mistretta was dusting off some framed documents in the corner of the archive room at Eastham Historical Society when he found what could be a priceless document. The piece of paper was an official recognition of the appointment of Elijah Knowles as Justice of the Peace in Barnstable County. Dated June 7, 1785, the document was signed by the Governor of Massachusetts, Samuel Adams. Society President Eileen Seaboldt recalled the moment Mistretta, the society's director, showed her the document. “He asked, 'Do you think this could be real?'” She remembers chills going up and down her spine when she looked at it.