I have no idea what’s the name of this one.
Edit: Thanks to the info from @[email protected], this is the Stropharia caerulea, commonly known as the blue roundhead.
Edit2: Another update on what we are looking at thanks to @[email protected]: It might also be Stropharia aeruginosa, commonly known as the blue-green stropharia
Ediblity unknown? OP, you know what you need to do. We need answers.
So I searched a little bit and according to my mushroom-page of trust it is edible: https://www.123pilzsuche.de/daten/details/BlauerTraeuschling.htm (in german).
There it says, that some people do not stomach it well but in general it does not have an exciting flavor and is best be added to other mushrooms. A bit underwhelming…
I will not eat it. xD