Favorite Pacific Northwest Mushroom Field Guides:
There are many Pacific Northwest mushroom identification books out there and I've bought them all. These are the 3 I recommend to anyone who is just getting started.
This delightful identification resource by David Aurora is comprehensive, entertaining, and includes a high quality key. The author is from California but speaks directly to PNW often. His field guide All That the Rain Promises and More (paid link) lives in my backpack.
Profiles of Northwest Fungi
(paid link)
A collection of "Mushrooms of the Month" articles published by Buck McAdoo of the Northwest Mushroomers Association which started in Bellingham WA. Each article describes a mushroom in detail, including photographs of most similar looking mushrooms in the area, making it an ideal resource for beginners. It also includes the nitty gritty in terms of taxonomy and microscopic observations for when your new hobby becomes a more serious passion.
(paid link)
This regional identification reference has evolved the identification key with an all photo based approach that makes identifying mushrooms very approachable for beginners.
Connect with Others in the Pacific Northwest:
There are many Pacific Northwest mushroom and foraging resources online but these are the few I've found most useful.
An "organization that encourages research, education, cultivation, hunting, identification, and the cooking of mushrooms."
This HUGE facebook group constantly feeds you photographs of the mushrooms growing in your area, right this second, with the added bonus of exposing much of the identification process in the comments.
I am constantly impressed with how current and high quality the regional mushroom information I find on Wikipedia. Please donate if you can.