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It was near Lewiston Idaho. They are caused by wind over wet snow and they're called snow-rolls or snow-rollers. Quite rare they say, these look as though the wind was blowing them uphill. You can see the trail from the one that looks as though it rolled back down a bit before stopping. They start out narrow and grow wider as they grow larger in diameter, hence the hollow looking centers. Those are pretty big ones.
This one may be a bit easier to get with a bit of snooping on the web.
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