Are these oyster mushrooms?

I have some mushrooms growing near the base of a dead tree in my yard.

mushrooms by vwfatmobile, on Flickr

Hard to see but they have gills
Are they oyster mushrooms?
I had some blue oyster mushrooms growing around here on purpose once.
Kind of looks like them.
And I've seen regular oysters on trees around here before.

I did a little searching and it looks like they might be.
One of the main indentifiers is the gills run all the way down the stem.
https://curativemushrooms.com/7-types-of-oyster-mushrooms-3-poisonous-look-alikes

Called "decurrent gills"

"Pleurotus ostreatus, is a common edible known for its oyster-shaped cap. One of the first things you should look for when trying to identify this mushroom is the presence of decurrent gills"

https://www.mushroom-appreciation.com/oyster-mushroom.html#sthash.CJbjmpo8.dpbs

They're not the best photos - as you pointed out, one of the key criteria in identifying them is the decurrent gills, which we can't see.

Aside from that, they should have a creamy-white or pale grey spore print (a useful way to improve your confidence about a mushroom ID). See this page for instructions about how to take a spore print.

The mushroom should also smell pleasant and even slightly of the ocean - hence the common name, Oysters.

The colour and shape of the cap look good to me though!

They'd be rotted by now, but next time pick one and take a picture of the underside!