Generally oyster mushrooms grow out of a tree, usually hardwood, and I have only ever seen them with a shape like an oyster shell — meaning that they are not circular, but have a distinct "back."

The mushrooms in this picture also have a little circle on top where the stem meets the cap, something I have never seen on a oyster mushroom. And the gills don't blend into the stem. I would say there is basically no chance of these being oyster mushrooms, unless they are some weird regional variant I am not familiar with.