[Ditiola]

If you search for Hygrophoraceae in Wilkipedia you get the following (with references):

"The Hygrophoraceae has been recognized by the majority of modern authors (eg, Singer, 1958; Bon, 1984; Largent, 1985; Boertmann, 1996; and Young, 2005), however, Eef Arnolds (1986) and Cornelis Bas (1990) have sunk the entire group into the Tricholomataceae. Some secondary sources (eg, Kirk, 2001) continue to use Arnold's and Bas' classification provisionally given the unsettled state of fungal nomenclature in the early 2000s. (Kuo, 2003) Young (2002, 2005) notes that though Moncalvo's analysis shows Hygrophoraceae to be polyphyletic, Tricholomataceae is even more so and will probably be split, so that adding the former to the latter will compound the problem. Young (2002) also notes that combining the two families would represent a continuation of the highly outdated concept that all white-spored genera belong in one taxon."

Hope this is of some use.

Peter