"The manufacturers of spawn started a very active propaganda by advertising in the magazines. They asserted that mushrooms could be grown in any outhouse or cellar, at the same time giving the impression that any one could be successful and that there were almost unlimited profits in the business. Many have been greatly disappointed, while others, who have had the right conditions for their growth, have been encouraged and made large profits."
January 1, 1970
https://en.wikiquote.org/wiki/Fungiculture