The Fraternal Order of Knights of Pythias is an international fraternity that promotes universal peace. It was founded in Washington, DC during the Civil War in 1864 by Justus H. Rathbone. The letters F, C and B stand for Friendship, Charity and Benevolence.
The three symbols on the headstone below are (left to right): Knights of Pythias, a Christian monogram for Jesus, and the Modern Woodmen of America (the original name of the Woodmen of the World).
Photos: Green Mountain Cemetery, Boulder, Colorado