I'm looking for a source of grass-fed (pasture-fed) beef and pork in the greater Boston area. Whole Foods has a tiny selection. Are there any other options?
How about heirloom turkeys?
For grass fed beef, there are several comprehensive prior threads which it would be worth your while researching.
For a general resource, you might want to familiarize yourself with Lionette's Market. Some of their beef (like some CSAs/farmers market vendors) is grain finished, but they are careful to differentiate 100% grass so you can get that info from them. They butcher one local pig (pastured, not certain if its not fed some grain) a week. And they do offer heirloom turkeys.
Chestnut Farms has a range of meat that is allowed to roam, hormone free, and fed what it has evolved to eat. http://chestnutfarms.org/ for more info. They do sell at local farmers markets and have a popular CSA program (i've been a happy subscriber for over a year now). I'm not sure if their turkeys are "heirloom", but they are just as well treated as the other denizens of the farm, and are available un-frozen and fresh to CSA members at thanksgiving (members must pre-order).
For a local farm, we love Stillman's. We are CSA members and do not by any meat from the grocery store anymore. They're fantastic.
Stillman's has heritage turkeys but they are sold out for 2009. You can get on the list for 2010.