Anderson, Sherwood. Winesburg, Ohio. (1919). Anderson's book consists in related short stories, a model for The Pastures of Heaven, and included grotesque and gothic elements, as well as treating the desire of rural people to move to the city.
The Wikipedia article on Steinbeck's The Long Valley describes the book as being thematically linked with The Pastures of Heaven. This collection of short stories explores the struggles of men and women against the individual, humanity, and society.
Understand how farming in the United States was rapidly changing. At the time Steinbeck had written The Pastures of Heaven farming in the United States was on a rapid decline. Steinbeck lived in these valleys and saw the decline first hand.
A History of California Agriculture from the Spanish missions in the 1700s to modern day farming trends.
Benson, Jackson. John Steinbeck, Writer. New York: Penguin, 1990.
Brighouse, Harold. "Rural Depression." Manchester Guardian 9 June 1933: 7. John Steinbeck: The Contemporary Reviews.Eds. Joseph R. McElrath, Jesse S. Crisler, and Susan Shillinglaw. Cambridge: Cambridge UP, 1996. 18.
Fitzgerald, Gerry. "Carmel Valley Inspires Story." Los Angeles Times (1886-Current File) 23 Oct. 1932: B16. ProQuest Historical Newspapers Los Angeles Times (1886-Current File). Arizona State University Lib., Tempe, AZ. 29 July 2008.
M.D. "A Rich Stream Marks Steinbeck's Tale." Chicago Daily Tribune 19 Nov. 1932: 14. John Steinbeck: The Contemporary Reviews. Eds. Joseph R. McElrath, Jesse S. Crisler, and Susan Shillinglaw. Cambridge: Cambridge UP, 1996. 14.
Moffett, Anita. "A Sheltered Valley." New York Times Book Review 20 Nov. 1932: 15-16. John Steinbeck: The Contemporary Reviews. Eds. Joseph R. McElrath, Jesse S. Crisler, and Susan Shillinglaw. Cambridge: Cambridge UP, 1996. 15.
Steinbeck, John. Journal of a Novel: The East of Eden Letters. New York: Viking, 1969.