Thanks Douglas. I have reassessed this situation and come up with Marasmius as the most believable option. They seem to dry up after rain when the sun comes, only to come back to life with the first hint of rain. The roots are very deep, suggesting an agrocybe, so I won’t rule that out yet. But the fact that they rise from the dead so quickly suggests Marasmius I ascertain.

These don’t really look like Galerina, not striate, and too viscid. Also they appear to be only on grass, and Galerina usually don’t appear with grass only, usually on moss and/or wood. (Although Galerina haven’t been studied everywhere, so who knows…)