I'm not CNM's Fungi expert but I've done some research becasue these were so cool and I think it is most likely to be some sort of inkcap, probably Parasola or maybe Coprinopsis
The cap in the front has numerous whitish granules, suggesting that when still unopened, the mushroom was enclosed in a membrane (the universal veil). Parasola lacks a universal veil. I used the name Parasola for this sighting (http://canberranaturemap.org/Community/Sightings/Details/2458403), on the assumption that what was on the cap was some rubbish. However, I think the mushrooms in the current photo belong to Coprinopsis or Coprinellus. In years gone by they were all in the genus Coprinus. If you want to see how these small coprinoid mushrooms can change as they open have a look here (http://www.cpbr.gov.au/fungi/images-captions/coprinus-sp-0249.html) and here (http://www.cpbr.gov.au/fungi/images-captions/coprinus-sp-0250.html) - and excuse the use of the name Coprinus in the captions.