As I helped Mama up the stone steps to the porch, I could hear a creaking and sure enough, there was Ben Prescott sitting and swinging on the porch hammock like it was any other day in the world but the one his Pop died. He just sat there, lanky and tall as life. What really surprised me was he had his favorite guitar in the hammock beside him. Like he'd just finished playing "The Big Rock Candy Mountain," or something. (Johnny Panic and the Bible of Dreams, Harper Perennial Modern Classics 2008, p. 223)
Plath wrote about the real life events that inspired this story in two letters to Gordon Lameyer written on 22 and 23 June 1954. Plath had recently visited Winthrop because her childhood friend Ruth Freeman's father passed away suddenly. Plath does not however, in either of the letters, make reference to the song. The original letters are held by the Lilly Library in the Lameyer Mss. Copies of the letters are in Lameyer's unpublished manuscript "Dear Sylvia."
After these letters were written, Plath herself went down to Eastham, Cape Cod, and stayed in the Hidden Acres area where she would later honeymoon, with Ted Hughes, in the summer of 1957. Hidden Acres is so hidden no one seems to know exactly where it was, though Plath tells Lameyer in the second letter that it is off the road to Thumpertown Beach.
Read more about the song here.
All links accessed 10 May 2013.