Where an I find accurate advice about local mushrooms
The picture you sent is probably the Spring Agrocybe, Agrocybe praecox.
We live in a great placer for mushrooms with lots of learning opportunities. There are mushroom books available, including "All that the rain promises and more." and if you're in the Coast Range, "Mushrooms of Marys Peak." In the Fall there are several mushroom festivals in October where you can learn about them, including big displays of picked mushrooms: Yachats Mushroom Festival, Oregon Mycological Society, Mt. Pisgah Mushroom Festival. Google them to find out about dates and times.