Small umbella shaped mushroom.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
Easy to agree visually. But, we'll be told it's impossible without a microscope and some spore!
THREE MARINE PROJECTS
I would agree with that but the most common mistake is to put this name to a "parasol" in woodland and it is almost always P. Leptocephala.
I'd say, Malcolm, off hand, that this is not a woodland photo - if ONLY posters would give us more information!
It really does not look like Mycena leptocephala - (searching for P. Leptocephala yields no useful material - so might you have the old name).
This picture has all the visual attributes of the lovely Pleated Inkcap (Parasola plicatilis) as you've already asserted.
IF we are to give agreements to photographs, then it can only be on the visual clues unless we have far less Blind Posting - which I normally leave well alone.
Not an old name but an old typist. Mixing my Coprinus and Mycena, it should be Parasola leiocephala. I will post an observation of this species for comparison.
Lat/Lng: 1.2097, 52.9481