I have been getting my lamb from Nick at Coolidge Variety in Coolidge Square, right across from the Deluxe Town Diner in Watertown. He sources it from Mennonite farmers in western Mass. He is a really nice guy and I try to support him whenever possible.
( Also the subs from the place next door, Emilios Homemade Italian subs and dinners, are quite good. A meatball sub and a side of the fried eggplant that you slip beside the meatballs is a guilty peasure of mine after which i need a nap. They got my vote when I asked them not to put lettuce on my Italian sub and the guy looked at me horrified and said " Who puts lettuce on an Italian grinder?" Boom. Loyal customer.)
But I would be interested where you get your lamb.
Do you drive up to get it, or do they deliver to the area?