These are snow bales formed in a few hours on the prairies of Southern Idaho and photographed by Tim Tevebaugh.
They're about 2 feet high and are a naturally occurring phenomenon requiring the right combination of temperature, humidity, wind speed, snow and flat or slight rolling open ground covered with a smooth layer of ice or crusty snow.
When the air temperature is slightly above freezing, with drifting snow and strong gusty winds of at least 25 mph the the bales begin to form by the wind rolling a bit of snow which clings because it's wet but rolls because the surface is icy.
The wind moves the snow continuously, picking up more snow as it rolls until it becomes too heavy for the wind to move or it comes up against an obstacle. They're very fragile, disintegrating if the temperature varies a degree up or down.