Beware of the Whispering Grass — Robert Kammen

This is a Sci-Fi Western set in Wyoming. It has a sprinkling of cowboys and Indians. A DNA sample of the San Pedros Mummy was intercepted by government agents and turns out to be a perfect match for the Roswell, New Mexico aliens. The action takes place in the Big Horn Mountains in which dwell the Nimeragar or Little People and the governments desire to have them exterminated.