Scleroderma Cepa
I have given up trying to identify this fungus. It is either a Scleroderma Cepa or a Scleroderma Citrinum. I have only found one of these, in the burned part of the forest and it was about 120mm across. If it is the Citrinum it is poisonous.
There is more information on these at this great website. http://australianfungi.blogspot.com.au/2010/07/39-scleroderma-cepa.html
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