Maude Ballou worked as King's secretary from 1955 to 1960, when King led the Montgomery Improvement Association and the Southern Christian Leadership Conference.
Ballou, who turned 88 Friday, is selling the items Oct. 17 in New York through Texas-based Heritage Auctions. People can bid in person or online. Ballou and Heritage Auctions say a portion of the proceeds will be used to establish an education fund at Alabama State University.
In an exclusive interview Tuesday with The Associated Press, Ballou recalled times both rewarding and frightening in those turbulent years, including an especially poignant moment with King in the mid-1950s.
"He said, 'Maude, I dreamed last night I died and nobody came to my funeral.' And that was very touching," Ballou said, her chin quivering. "And I said, 'Oh Martin, that's not going to happen. Nothing like that's going to happen to you.'"
King was assassinated in 1968 in Memphis, Tenn.
Some of the more than 100 items are unique, so it's difficult to put a value on them, said Sandra Palomino, director of historical manuscripts for Heritage Auctions.
"We're really relying on letting the market decide what the value is going to be," Palomino said.
Items awaiting sale include a handwritten letter King sent to Ballou while touring India in 1959 to learn more about Mahatma Ghandi's campaign of nonviolent resistance.
Another item is a typed final page of King's "I Have a Dream" speech, according to the auction house. The page was sent to Ballou on Jan. 31, 1968, several weeks before King was assassinated, by Lillie Hunter, bookkeeper for the SCLC and secretary to Ralph Abernathy.
Other items include King's handwritten notes for a 1959 speech to inform his congregation that he would be leaving Dexter Avenue Baptist Church in Alabama, where he served as pastor in the 1950s and was involved in the Montgomery bus boycott.
In the notecards, King said he was doing the work of five men by travelling for speeches, leading the church and the Montgomery Improvement Association and doing "endless work" with the Southern Christian Leadership Conference. King later moved to Atlanta where he became co-pastor of Ebenezer Baptist Church and continued his work with the SCLC and the struggle for equality.
Also for sale is a 1957 Alabama Department of Public Safety list of people and churches considered vulnerable to attacks. King is No. 1 on the list; Ballou is No. 21.
In 2011, King's estate sued the secretary's son, Howard Ballou, in a bid to take possession of the items, but the courts ruled against the estate.
Maude Ballou, who has a business degree from Southern University in Baton Rouge, La., was working for a radio station when King asked her to be his secretary. Her husband, the late Leonard Ballou, was a friend and fraternity brother of King.
After working for King, Maude and Leonard Ballou moved on to what is now Elizabeth City State University in North Carolina, where Leonard Ballou was an archivist. He apparently stored some of the material in the university's basement, unbeknownst to anyone, until it was discovered in 2007 and returned to the Ballou family.
"I don't like to get rid of anything. I like to keep it. But I know we must share. If it's going to help, we have to share it," Maude Ballou said.
Some keepsakes are staying with the family, including a copy of King's book, "Stride Toward Freedom" with a handwritten note on the inner cover, "To my secretary Maude Ballou."
"In appreciation for your good will, your devotion to your work, and your willingness to sacrifice beyond the call of duty in assisting me to achieve the ideals of freedom and human dignity for our people, (signed) Martin."
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