Great find! I suspect they may be the same as the mushrooms in this spotting:
http://www.projectnoah.org/spottings/16353624
Do they look the same? Please note that that is mislabelled, it is not a Lepiota.
Do you have any more pictures, or if not can you get any? I have been hoping another spotting of this mushroom would come up because it is very unique looking and I can't work out what it is. Perhaps it's something undescribed. If you do find them again, perhaps you could collect and dry some?
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