looks like blastos trying hard to get a little light.... blasto's are a large polyp stony meaning they have a skeletal base... much like in the lower part of your picture mushrooms will not have this.
yeah they kinda look like blastomussa merletti to me, especially cuz of the green centers and the ribbed outer ring and what we can see of the stony base. nice lookin!!
actually, now lookin at the base more, i dont kno if its merletti or not, sometimes merletti has little "stems" almost where the polyps come out of. either way, its def a blasto like most stated before me
As late as the early ninties is was common for wholesalers to ship two or three blasto colonies accidentally when they sent out a box of assorted mushroom rocks.