Images courtesy of Stack's

Varieties:
Shillings
   Noe 1-A
   Noe 2-B
   Noe 3-C
   Noe 3-D
   Noe 3-C

Sixpence
   Noe 1-A

Threepence
   Noe 1-A

Significant examples:
In the February 2005 issue of NUMISMATIST (page 63), William Anton offered a Willow Tree Shilling for $750,000.00, describing it as follows: "Full round planchet, size of a half dollar, fully struck up Willow Tree, full complete struck up date and with no defects whatsoever.  Super Gem Uncirculated."

Sources and/or recommended reading:
"The Silver Coinage of Massachusetts" by Sydney P. Noe (out of print)