Seems to me like Setulipes is still pending, as well as Gymnopus and Marasmiellus (former Micromphale) which are polyphyletic. Strange to make all these changes before the limits are better known..

mention all kinds of plant material, but mainly coniferous (rogersmushrooms for example, even includes grass and manure).

Funga Nordica says “sticks and needles of coniferous and deciduous trees and scrubs, grasses and sedges, in oligotrophic localities”.
It’s btw included in the genus Gymnopus now by Antonin & Noordeloos…

Marasmius androsaceus but as far as I know (from what I’ve read) that is just on conifers.
Irene, whats your source that says it grows on deciduous leaves?

Marasmius androsaceus to me. I usually find it on conifer debris, but it can apparently grow on leaves too.