It's always a good idea to put magic mushrooms in your dungeon. I firmly believe that temptation and bad decisions lead to enjoyable role-playing opportunities. In that spirit, and because nothing says OSR like a ridiculous random table, here's a d30 table on the effects of magic mushrooms. PC's beware: these aren't your hippy uncle's magic mushrooms!
*If you don't have a d30, I recommend using the free Crawler's Companion app from Purple Sorcerer, available at http://purplesorcerer.com/crawler.php.
Click here to download the hand-crafted PDF from Google Drive