Sava: Not quite pretty, but common.
I made a stop at 5-6 places along highways 26 and 6 yesterday and today (Coast Range),
and saw these "everywhere".
They grow in leaf litter.
Their spores are white, despite the various gill colors we see (yellowish when young).
They often look old and then they are really old, they just don't decay easily.
Genus? Even better: genus and species?
Paul W: The white mycelia at the base point me toward Leucopaxillus.
Judy: Not Leucopaxillus - far too slender, and gills never darken like that older one.
(I did a key to Leucopaxillus in the late 1980's for Key Council,
and this does not fit the genus).
L's mycelial matte is in the soil, and often quite extensive,
not on the stipe as this is.
This more Collybioid or like a Fayodia.
It also looks a bit like a Tricholomopsis platyphylla,
(esp. the stature type and colors) but don't think it has such a fuzzy lower stipe,
and grows attached to rotting wood.
Other that those, it looks very familiar to me but can't come up with more of a name.
Sava: Paul, your guess was not bad at all,
but Judy's explained "why not Leucopax" better than I would.
Thanks, Judy. Judy's also right that this is Collybioid.
It's Gymnopus peronatus (used to be Collybia peronata),
a European species that's only recently become common on this continent,
and only in the PNW. Trudell & Amiratti call it a mystery.
I just did some microscopy of this mushroom and posted it on MO:
http://mushroomobserver.org/99920?q=PK6C .
Dick B: I'm wondering if you found that some of the gills were free.
From the picture it looks like some might be free and as I recall
Trudell notes that gills are free.
In the past I have found a similar mushroom on Powell Butte and
although the gills did not appear free if you twisted and rocked the stipe
you could separate it from the cap cleanly.
Sava: Yes, in some the gills did appear free.
I could see various stages of gills seceding from the stem.
And, indeed, the cap and stem can be separated quite cleanly.
I didn't notice it, but just checked.
Funny, an hour ago I threw this bunch of mushrooms in garbage,
then had to take them from there to do your test.