I remember reading somewhere that this stuff (or yellow variations of it), is harmless. It is not. According to Professor Roy Watling this ‘Dog’s Vomit Fungus’ fuligo septica has spores that can enter the pores in your skin and cause VERY NASTY THINGS to happen there. It appeared in my grass this time last year and it is there again now. If you get it, don’t simply mow it. Use a plastic bag over your hand and do that dog-poo thing with it. Tear up the grass to lift it up. Bag it and bin it. Best not to breathe while you are doing it. And wash your hands. Here endeth…. etc.