Taraxacum sp. (Dandelion)
Note that at higher altitudes, this could be the native dandelion, Taraxacum aristum.
Environmental weed in NSW and Vic (as Taraxacum officinale).
http://keyserver.lucidcentral.org/weeds/data/media/Html/taraxacum_officinale.htm
Gallery
Regional distribution
Taraxacum sp. is listed in the following regions:
Map distribution
Taraxacum sp. has been reported at the following locations: