Very similar to Clitocybe nuda. According to Denise Gregory’s key to Clitocybe in California, they can be distinguished based on the cap color when young. In the case of C. nuda they should be deep violet or purple. C. glaucocana, on the other hand, is light violaceous, light blue or faintly purple when young. It would be nice to know if there are other reliable ways to distinguish between the two species.
This species is listed in Fungi of Switzerland, Vol. 3. The photo given there is of a mushroom that could be described as white with a hint of purple. They are much paler than the photos shown here (as of March 2008). Even so they say “This species is sometimes regarded as a variety of Lepista nuda. There are no microscopic differences between the two taxa; therefore, only macroscopic characters can be used to separate them.” They go on to say “L. glaucocana is always characterized by pale, washed-out colors. Also, the odor of this species is always somehow unpleasant not pleasantly aromatic as in L. nuda.”
The characteristic odor I associate with L. nuda is that of frozen orange juice, but it isn’t always present. However, I have never noticed what I would call an unpleasant odor in a fresh blewits. As far as taste goes, in California I’ve found that lighter colored collections especially ones associated with cypress are often bitter.
This whole group is itching for some DNA and mating studies.