Alice Pelkey and Ray Brock both taught at the Stockbridge School (a "progressive" private school, located about 2 miles from Tanglewood). A lot of well known people graduated from there, including Chevy Chase and Arlo Guthrie. (So did my brother, but you've never heard of him.)
Alice was a nice kid. Ray was a fun-loving, heavy drinking, heavy smoking biker type - very romantic, I suppose, in hippie days. Everybody loved him, including Alice, and sometime in the mid-60's, Alice and Ray got married.
Why they left the school, I don't know. But Alice quickly discovered that earning a living was not Ray's strong suit. Alice loved to cook and found a side-alley storefront in Stockbridge. With a lot of help from her friends, she opened her restaurant. In fact, aside from providing the title for the song and movie, the only significance of Alice's Restaurant was that it provided the money to pay the mortgage on the abandoned church "they" bought.
In the 60's, it was quite fashionable to buy old churches and convert them into homes. Trinity Church, in Gt. Barrington, was available, and that's what happened - sort-of - well, Ray removed the pews to make room for motorcycles - and he put in a ramp - and part of the outside got painted. (I'll skip the legal stuff about use restrictions on consecrated ground).
Alice's restaurant was not a smashing commercial success. Alice's marriage was not so great, either, and both became history before 1970. The church, now Ray's (with Alice still paying the mortgage), was the center of the universe for a vast number of hippie types (including me). Most were escapees from NYC, who now lived in the area. Some were weekend warriors, who took off their suits and ties and let their hair down (literally), whenever they could. Everyone was welcome.
And then - DISASTER!!! Alice decided not to pay the mortgage on Ray's church. So, when the money from the movie ran out, Alice didn't, Ray couldn't, and the bank foreclosed on an era.
The church was privately owned by "outsiders" for a number of years before Arlo Guthrie bought it in the early '90s. It now houses Arlo's foundation.