Many of the cemeteries of Idaho have been identified and are listed on the Idaho Historical Society's web site. Some of them are also listed on the USGenWeb site for each county in the state.
An indexed collection of tombstone inscriptions is Cemetery Records of Idaho, 12 Volumes. (Salt Lake City, Utah: Genealogical Society, 1952-68; FHL book 979.6 V3c; films 824262 items 3-266).
The Daughters of the American Revolution (DAR) Collection also contains some inscriptions from Idaho cemeteries.