if you haven't seen it already, check out the links i posted in the sticky thread at the top of the forum.
Washington county is tough..it is mostly private farm land. get out and knock on doors, but don't be too surprised if you get a lot of No's. most of the land is either hunted by the owners or leased to hunters/guides/clubs.
you can head to the coast and hunt tillamook bay and the coastal areas there..get a map and check the area for the public access. i don't hunt it personally, so i can't direct you to any spots.
Sauvie island is close to WA county.
if you want to hunt upland game type birds you can get into Mountain Quail, Blue, and Ruffed Grouse up in the Tillamook State Forest. the roads off of Hwy 6 around brown's camp are a good place to start. get yourself a map (Oregon Atlas is a good one) and hit the logging roads.
Friends Don't Let Friends Shoot Mossbergs.