Stillman's at the Turkey Farm is a small family farm committed to humanely raising pastured animals. They offer a meat CSA for six or twelve month periods, featuring a combination of beef, lamb, pork, and chicken. The prices and pick-up locations are listed here: http://www.stillmansfarm.com/meatcsa.html.
Stillman's at the Turkey Farm also travels to Boston-area farmers markets with their meat: http://www.stillmansfarm.com/turkeyfarmfarmersmarkets.html.