Jmills Yes, these are oysters; probably Pleurotus pulmonarius. They are past prime condition, though. They are a bit dry and the gills are turning yellow. They would be chewy and probably pretty tasteless, at this stage.

S_Proctor I agree with your proposal. Did you smell it? I just did a spore print of P. nidulans and the stench was unbearable for two days.