Packrat den in the rocks. Some call them trade rats. A bit like crows, they like to pick up objects and bring back to their nests. They seem to have an eye for beauty. Some say they have a taste for the gaudy.
When they find food they may put down their found object in order to carry that food.
Their are tales pf prospectors going to the flour stash in their dugout and find the container chewed open and flour scattered about with tell-take tracks through. The prospector, after warming up to language that could make a burro blush, would find his eyes wide and his jaw dropped. In order to gather the flour the trade rat had left a beautiful golden nugget.