According to Bill Gerth at the OSU Plant Clinic:
That’s a folding-door spider (family: Antrodiaetidae) from the genus Antrodiaetus. There are several native species in Oregon, but you need to get a really good look at a male specimen to determine the species. The specimen in your photo is either a female or a juvenile, so you can’t tell the species on that one. For comparison, here is a link to a photo of a specimen that looks similar to the one in your photo…
https://bugguide.net/node/view/751387

Here is another link that has some nice distribution maps for the various Antrodiaetus species….
https://www.biodiversitylibrary.org/page/4753451#page/406/mode/1up

Folding door spiders live in silk-lined tubes in burrows in the soil, somewhat like trapdoor spiders. Instead of having a trap door, though, they have an extension of the silken tube they live in that lies on the soil surface and is ornamented with soil surface debris. Because of this camouflage, the tube entrances are pretty hard for a person or predatory animal to find. The spiders wait in the tube entrances at night for unsuspecting prey to wander by and then pounce on their victims.

Wyatt Williams
Sept. 7, 2018, 9:08 a.m.