Chorophyllum rochodes* is a known as the shaggy parasol mushroom and is classed as edible. There are many other mushrooms of similar appearance, however and I strongly discourage people from eating this genus or any of the related ones, such as Lepiota. The risk of fatal poisoning due to a mistaken identity is real and the consequences too awful to contemplate.
There are in addition many reports of people eating supposedly edible species in this group and one person has been violently ill while the other has not been affected.
edit 17/04/2016 The specimen pictured above is Chlorophyllum brunneum.
Another member of the genus, Chlorophyllum molybdites (below) has a very similar appearance, but instead of white gills, they are feintly green. It is not a deadly mushroom, but it may make you very sick and is a common cause of mushroom poisoning in North America. The nature of the poison in this mushroom was a mystery for a long time, particularly since it doesn’t affect all people at all times. It was revealed in 2012 to be a protein called molybdophyllysin by Yamada et al. This protein is similar in structure to components of some other fungi and bacteria, but the other compounds are not toxic. It is heat labile, beginning to break down at 70 degrees, which may explain why some people, including the Cribbs report having eaten C. molybdites with0ut ill effect.
I won’t elaborate further in the identification of these mushrooms, since I do not advocate even considering them for consumption. And that says something!
As a footnote, there is a report of the effects of eating this mushroom in the Medical Journal of Australia, by local academic Lindsay Mollison. I note that his report is in December 2011 and that he speaks of doing an extensive internet search to find out what he had eaten. Perhaps his experience was just prior to when I made this original post in July 2011. A shame.
*A paper by Vellinga in 2003 revises Chlorophyllum and Macrolepiota in Australia. She says that we don’t have Chlorophyllum rachodes in Australia, but a similar species dubbed C. nothorachodes. Specimens formerly referred to here as Chlorophyllum rachodes were found to be Chlorphyllum brunneum, and Macrolepiota procera, a northern hemisphere species, does not occur here. Although her paper does help to sort out the state of the species in Australia, recent evidence suggests that her survey is not complete.