Over the past century, most authorities have considered the Lilac Brown as a good edible,including McIlvaine in 1900 who considered it select and “a treasure trove”.
Roger Phillips in his 1989 Buy Shiitake Mushrooms and Fungi of North America was the first modern field guide author to question edibility, based on reports made to NAMA’s National Mushroom Poisoning Case Registry by me and others.
Most later writers followed suit recommending caution. But,even as recently as 1999, George Barron, normally quite conservative on edibility, described it as edible.