I'm going NO. Oysters grow on dead trees almost always. They do NOT cup upwards like this. They may be edible (I wouldn't eat them), but they are not tan/white oysters in my opinion (and I've collected and eaten a LOT of white/tan and golden oysters).
Oysters do cup upwards, but only when they are about sporulate and not quite as drastic as the ones in this picture. It's about the only way to tell that they are ready to harvest before they make a mess of your grow area.
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.
Not pleurotis species of any kind. It should have gill lines(don't know proper term) running all the way down the stem. They also usually grow on wood not grass