David Bloom, Freeman's vice president of manuscripts and books, notified the FBI this month of the discovery after determining that the manuscript had been reported stolen in the 1970s by Buck's heirs, who suspected that an employee or someone with access to the house had taken it.
Bloom said the document contained "a large number of annotations in her hand, including changes of phrases that would be of real interest to Pearl S. Buck scholars." The consignment also included several letters to Buck from world figures.
Bloom did not identify the consignor, but said the person appeared to have taken the manuscript in "with all innocence and good faith."
Bloom said the FBI told him it did not plan to file criminal charges.
The Good Earth, a novel about village family life in China, became an immediate sensation upon its publication in 1931, and established Buck as one of the few Westerners with intimate knowledge of life in China before the communist revolution. Buck, the child of Presbyterian missionaries, spent much of the first half of her life in China.
"For two generations of Americans, Buck invented China," Peter Conn, a professor of English at the University of Pennsylvania, wrote in a 1996 biography of Buck.
The Good Earth, the second of Buck's 70 novels, won the Pulitzer Prize in 1932.
After Buck won the Nobel Prize - she was the first American woman to win the honor - she was set on a course as a leader of civil rights and women's rights, and as a pioneer in international adoption and racial understanding.
Endowed with sudden wealth and fame, Buck settled on a farm in Bucks County after returning to the United States in the 1930s. She and her second husband, Richard Walsh, her publisher, raised seven adopted children on the farm in Perkasie.
Though some of her later work was poorly received by reviewers - many critics questioned whether she deserved the Nobel - Buck was cited in several polls in the 1960s as one of the most popular women in America.
Today, her restored two-story stone house houses a museum.
Green Hills Farm also is the site of the offices of Pearl S. Buck International, the philanthropy the author founded in 1964.
"We're so excited about what was uncovered," said Janet L. Mintzer, president and chief executive of Pearl S. Buck International, whom the auction house expert first called when his suspicions were aroused about the provenance of the manuscript.
A curator at the museum compared some of the typewritten pages from the recovered manuscript with a page typed on Buck's typewriter, which is on display at the Bucks County house. They matched.
Buck's son Edgar S. Walsh, administrator of the estate, said his heart jumped into his throat after getting a call about the manuscript he had reported stolen more than 30 years ago.
"When I heard a manuscript had been recovered, I said, 'Bingo!' " said Walsh, 70, of Greenwich, Conn. He said the estate, which owns the literary rights to Buck's works, would claim ownership of the manuscript.
Though the estate and the foundation have been at odds over ownership of some of the author's legacy, Walsh and Mintzer expressed hope that the recovery of the manuscript would renew interest in a writer whose work is less known to more recent generations.
"So many people today are not familiar with Pearl Buck," Mintzer said. "We hope this generates new interest and helps us continue her legacy."
Contact staff writer Andrew Maykuth at 215-854-2947 or firstname.lastname@example.org.