|Community of Christ Temple, Independence, Missouri. (c) 2010 Daniel Ortega|
The Community of Christ, formerly known as the Reorganized Church of Jesus Christ of Latter Day Saints, is headquartered in Independence, Missouri and shares an early history with the Mormon church. Simply, after the death of Joseph Smith there were questions of who should lead the Church. Those who went to Utah with Brigham Young are the Mormons and those who stayed behind in Independence and the area are the Community of Christ. (This is a simplified explanation, you can read about the history of the Community of Christ church here).
The Community of Christ has an archive and library that would be of use for those with Community of Christ ancestors as well as Mormon ancestors.
The Archive holds primary source materials pertaining to the history of Community of Christ, which would include early Mormon church history. Online they have a research request form as well as information about the archive.
According to their website, the Library has over 20,000 books as well as audiocassettes, periodicals and videos. You can conduct a search of the library catalog through their website. Read more about the library here.
You can read about some of the Community of Christ's historical sites on their website. Their temple in Independence includes a museum with early artifacts. According to it's website, the museum " collects, maintains, and exhibits artifactual materials, relating to the mission and history of the Restoration (LDS or "Mormon") Movement, mostly from the United States and Canada, particularly the states of New York, Ohio, Missouri, Illinois, and Iowa, with some materials reflecting church activity in Australia, the British Isles, French Polynesia, and other international missions." Admission to the museum is free. When we were there, we were told that photography is not allowed in the museum.