My ears were burning ..... and I believe Parcelpostguy is going in the right direction on this.
Very interesting cover!
Ignoring the flag cancel, it has some resemblance to a down-the-route RFD cancel. The star made me think of "Star routes", which were essentially private contract routes to carry bulk (pouched) mail between towns occasionally serving a few patron boxes along those routes, very similar to RFD service.
While it does not exactly cover the time period, I see in Postal Bulletin #13724, dated March 28, 1925 an announcement of a star route going through La Grande, OR:

So star routes were certainly used in that part of Oregon, confirmed by the listings for the offices in Union County, Oregon from the 1935 Official Postal Guide noting several of the towns there have star routes serving a small number of patrons:

The nationwide employee lists stop in 1911, so no luck there.
Bottom line on my guess: you have a cover picked up by a star route carrier who "protected the revenue" with a star and his name and deposited it at the next office he came to. If it is such a use, a provisional star route cancel is very uncommon. The first I have seen. Mail addressed to/from star routes in also challenging to find.