Spotting

Thank you for your effort of making extra photos, Max :) Much appreciated! And these photos confirm my suggestion: lack of annulus, a dark velvety stipe and yellowish gills that are not too crowded. This is a Flammulina species. I'm not familiar with New Zealand species of this genus, though, so you might want to ask local mycologists for more information on that.

Photos updated for you both. Underside and aged mushrooms

That would be great, Max Gallagher!

I will try and get a photo of the underside later in the week

I'd love to see the underside, for I predict it lacks an annulus (ring around the stipe) and has a velvety stipe. Based on what I see from the photos, I believe the pileipellis (cap cuticle) seems too smooth and rather hygrophanous (cells are able to soak up water, changing the cap colour with different levels of humidity, as seen on the edge of some caps). Therefore I think this to be Flammulina spec, rather than Armillaria spec.

I will look into it

Thanks António!

Nice find Max,i think it's a Armillaria species, https://www.google.pt/url?sa=t&rct=j...