Scleroderma citrinum

Scleroderma citrinum is the commonest species of Earth Ball in the UK and occurs widely in woods, heathland and in short grass from Autumn to Winter. Scleroderma citrinum may be referred to as Scleroderma aurantium in older texts.

Earth Balls are superficially similar to Puff Balls but whereas the Puff Ball has a single opening on top through which the spores are dispersed, the Earth Ball just breaks up to release the spores. Scleroderma citrinum has no stem but is attached to the soil by mycelial cords. The peridium or outer wall is thick and firm, usually ochre yellow externally with irregular warts.

References

Collins Gem Guide: Mushrooms and Toadstools, Stefan Buckzacki 1982.
The Observer's Book of Common Fungi: E M Wakefield, OBE, 1964. pub, Frederick Warne & Co Ltd.