It is interesting to note, that in the USA the study of brown mushrooms was halted, because many/most of them contain hallucinogens. Hallucinogens were mandated to be classified as poisonous. Even to this day, campaigns happen when mushrooms appear to convince the public that all mushrooms may be poison . No funding or support will be given to classify brown mushrooms. However, if you can read Spanish or German you may find many books with proper classification. As brown mushrooms in the USA have been studied by other countries, and untranslated works are out there.
That is really interesting. They try so hard to keep us from ourselves that we fail to learn anything. I need to keep an eye out for more identification books.