Secotium

About

Secotium is a genus of fungi in the family Agaricaceae. The members of this genus are closely related to ordinary Agaricus mushrooms, but do not open out in the usual way; this has given rise to the term "secotioid" for such mushrooms in general. They are thought to form an evolutionary link between agarics and gasteroid fungi. Secotium is a widespread genus, with species that are predominantly found in warm and arid regions.

Summary from Wikipedia