This is a Noe-9 Oak, one of the less common varieties in the series and, to my eye, one of the prettiest, with a neatly balanced design. From Stack's Oct-2005 sale of the Ford Collection, lot 31 - earlier F.C.C. Boyd.
Ron Guth: Massachusetts "Oak Tree" Shillings include the following die varieties:
Sources and/or recommended reading:
Noe, S. P. (1943). The silver coinage of Massachusetts. New York, NY: American Numismatic Society.
George H. Earle - Henry Chapman 6/1912:1921 - F.C.C. Boyd - John J. Ford, Jr. - Stack's 10/2005:24 - Dwight Manley - Heritage 8/2010:3006, $161,000