These mushrooms start off (as seen in my last fungi photo that I posted) with very pale caps and then darken and create these wonderful patterns. They remind me of Hot Cross Buns that you can buy around Easter time : ) There were lots of this kind of mushroom on the edge of Fish Creek park at the eastern end recently, but they quite quickly dried and shrivelled up, forming most unphotogenic (if there is such a word), shapeless piles on top of the mulch.

Any chance this might be Cracked-Cap Mushroom / Agrocybe dura?