This class corresponds to mushrooms in the phylum Basidiomycota which mushrooms produce spores in their interior.
It is a polyphyletic class that should be proposed as a identification when no finer ID is immediately possibly.
It includes (but isn’t limited to):
An unrelated subgroup of Basidiomycota which produce their spores on the inside. http://www.anbg.gov.au/fungi/two-gasteromycetes.html; http://en.wikipedia.org/wiki/Gasteroid_fungi