Those look exactly like those tiny little beads you get at that science store found in the large malls. When you add water to them, they enlarge and look exactly like that. Or they could be those fragrance beads without any fragrance, or those beads that you can use for potted plants in place of real soil. You can find those liquid beads just about anywhere for use with all kinds of things.
Why someone would dump them out in the desert is beyond me. Unless they were stolen off a shipment truck, and whoever stole them got bored with them and ditched them way out there. Who knows... people do dumb things.