easy way to spot shrooms in the northwest is to look for a conical head and black gills that are tightly packed, usually have thin stems but i've found they are very proportional to the head.
Spore printing is also very easy to do and easy to tell whether or not its a good shroom, black to purple/brown spore print means its probably a good shroom.
I find my shrooms where horses have been, mainly cause i dont have friends with cows, and i dont own any myself. The best shroom i've found so far is this little yellow guy which doesnt get very big but its the strongest shroom i have yet to find, its got grey gills but dark black spores, and a small bowl shaped head which is bright yellow, I have found this only growing directly on horse dung.
Also one note about the shroom books you'll find, many of them give certain seasons when you can find these, its not really true, I've been able to find shrooms all year long, just as long as its moist outside, and there isnt too much sunlight, or its too cold.