UPDATE: The mystery may have been solved. See below for images.
1) Mark, a listener from Florida who called in on the 5/13/18 show, found a rope sticking up through the sand when he stopped by the roadside in the Mojave to relieve himself. This photo shows the cloth bags within a bag that contained a small statue or amulet.
2) Side view of the metallic statue including the markings on the helmet
3) Front view of the man, his facial expression, and whatever tool, weapon, or instrument he is carrying.
Author of "Mojave Mysteries," M.L. Behrman noted the figure's similarity to an ancient South American statue. "Same pose, loincloth style and similar implement."