Parks, who died in 2005, became a civil rights icon when she refused to give up her seat on a bus to a white man in Montgomery, Alabama, in 1955. Her arrest triggered a 381-day boycott organized by the Rev. Martin Luther King Jr.
Howard Buffett, who is a philanthropist, said he was drawn by the cache's historic importance and became involved after seeing a TV news report it.
3 generations of Buffetts on giving
"This is an incredible part of history, and to have that history locked in a chamber somewhere is not right," Buffett said.