I'm assuming Marasmius because of the thin, black stem and the small cap. If you have the Tasmanian fungal guide by Gates & Ratkowky, you'll see that this is a bit like the as yet un-named Marasmius that they include as Marasmius 'angina'.
Paragymnopus is a possibility. The past decade or two have seen various 'Marasmius' species move between long-existing genera or into newly-defined genera. It would probably be sensible to change Marasmius sp. to 'Marasmius s.l.' (meaning Marasmius in the broad sense) or to the adjective 'marasmioid'. I'll think about it.