Thanks Dimitar and Christian,

I believe you are right with it been Agaricus arvensis I have not seen a pale yellow verity before with the bush been a strange habitat for them. Its did have a odd smell which I did not recognize and bruised yellow then brown now that I think about it. The spores are also the right size and shape.

Thanks for your help
Clive

Not sure whether arvensis is an appropriate name Down Under, but
what I see here is really arvensis like. It should have a rather
weak pleasant, slightly almondish odor, not always easy to
detect. But never unpleasant.

Did you notice any smell or staining reactions when handled? Great first photo, by the way.