The calvatia genus comprises most of the largest puff balls in the world and in my opinion the best edible puffballs in the country. Australia has a handful of different calvatia species that range from golf ball size up to softball or bigger, over 150 mm across. They start out white, with or without a sterile base, The species in the photo above has the sterile base. As the puffball matures it becomes larger and softer and begins to change colour as the spore mass matures. The colour they change to and that of the mature spores along with the presence or absence of the sterile base are the ways the different species are differentiated visually.
I have been unsuccessful in properly identifying the calvatia puffball I have found this season, its a bit of a odd one out. Generally calvatia species fall into two categories the ones that turn yellow or red then brown, the spores do the same ending up a mustard to olive-brown colour at maturity or the ones that turn purple then brownish, the spores end up bright or dull purple. The species I Have found turns slightly yellow then dark brown and ends up with a grey slightly woolly spore mass. I have been unable to satisfy myself as to its true identity, Its closest to c. cyathiformis but I’m not really sure. Wikipedia list 58 species globally, I can find good reference to about 9 species in Australia tho I am skeptical about a few of them. The species are c. craniiformis, c. lilacina, c. rugosa, c. fragilis, c. candida and the three I’m not so sure about c. gigantea, c. fusca and c. olba. As you can see from some of the links the details are sometimes a bit thin on the ground! All of them should be edible while they are young with firm white flesh the main factor will be their palatability. Some species are reportedly bitter while others may have a slight laxative effect.
These puffballs start out white and round on top, pear shaped with the sterile base. The skin is leathery with a lizard skin sort of pattern of cracks or scales, this will vary a bit depending on weather conditions. As they mature the fruit body swells and flattens out somewhat, they also develop some folds and wrinkles. The biggest one I have seen was about 120 mm across. At maturity the skin becomes dark brown and begins to flake off exposing a second thin layer with the grey spore mass showing thru in cracks. The sterile base is quite prominent but smaller then some other species, the mature tissue is quite woolly and brown. The spore mass starts out pure white before becoming grey and powdery, it seems to have a slight woolliness to it. There is a thin membrane between the base and spore mass. I find these growing in grass in parks and roadsides some times with poorer soils. I have seen one patch forming a large fairy ring. Fruiting over summer and into early Autumn. There are a range of smaller white puff balls that grow in similar areas the most common species are Vascellum partense and some bovista species, these are also edible tho not as good. There are also the lycoperdon puffballs that grow more often in forested areas. The calvatia tastes like egg or potato when sauteed in butter. They should only be eaten while they are young and firm before they reach their full size. Once mature care should be taken not to inhale there spore dust. To see more of my puffball photos click here.
Update: I have had a sample of the puff balls sequenced, the results came back as a 98 percent match for Calvatia fagilis, which was unexpected. In my opinion a 98 percent match could mean these are a different species so as always more work needs to be done. C. fragilis is very closely related to c. cythiformis so i will just leave my original ID as is. I have since had another sample sequenced, it came back as 98% Calvatia cyathiformis (MF686508)