Looking for some confirmation that these beauties are Oyster Mushrooms?

Take this with a grain of salt obviously, but I put the image into a plant identification app and it came up with Lepista personata.

Matches the growing in grassy areas and cupping upwards properties from your picture.

Hopefully you’ll get some experts chiming in. I am not. I just found your question interesting and did some searching.

The biggest thing I see to check is whether the gills run vertically *and extend into the stem. If the gills stop at the stem, avoid.

https://grocycle.com/oyster-mushrooms-guide/#:~:text=They should be smooth with,white to brown on top.

Edit: actually you may not need to avoid if the gills don’t run all the way. If they don’t, there’s a good chance they are Elm Oysters, but elm oysters are edible. I’m basing this info on the above link. It seems pretty clear that what you have aren’t the dangerous varieties listed on that page.

Compare to Pleurotus, growing from buried wood. The ones to rule out here would be the worrisome Clitocybe dealbata group