Identification: Some kind of oyster

I found these growing on a stump (probably cottonwood) in a shaded forest...look like oyster mushrooms. There was another kind growing hereabouts but that one looked 'pearlier' and these look kind of dark.
Any help in identifying this would be appreciated :)

 

I'm leaning towards Pleurotus ostreatus

 

They look a little dark for Pleurotus. Panellus serotinus is another possibility, but they normally have yellowish gills.

 

Thanks for the reply vitog :)
They might be darker than they should look because I underexposed in the dim light...and they are damp from recent rain.These definitely had pale gray gills, just a hint of an undefined warmer colour. The spore print is finally showing and appears to be white.
I just looked this up and the trees Panellus serotinus is fond of are not common here. ("...beech and birch but also on alder, ash, oak, willow, elder and elm.")
Wish I knew what the rotten looking stump was.
For what it's worth, something similar is growing a few kilometers south of here on a felled cottonwood/aspen:

 

Hola Artemis,
Beautiful photos! I agree most likely Pleurotus ostreatus rather than Panellus serotinus, because at that state of maturity the characteristic wacky colours of P. serotinus would be showing up.
However, if the spore print turns out to be brown/beige rather than white, and given the size, Crepidotus mollis is also possible. I've been surprised a few times this season by initially seeing what appeared to be Pleurotus then seeing evidence of brown spores on the gills.
If it had been on conifer, and thinner fleshed than these appear to be, then might've been Pleurocybella porrigens.
cheers!
frog

 

Thanks for the nice words Frog :)
The oysters were gaining a bit of a brownish hue as they started to molder away but the spore print is definitely white. I decided to leave them to rot on some cottonwood logs behind the house...we shall see what happens!
Pleurotus ostreatus is what I will have to go with I think. The whole taxonomy thing is in such a state of flux it's just frustrating to pin it down- I greatly appreciate the input from all here.