The Liathghorm salmon is prized not only for its flavor, but the unique psychic properties of its flesh.
Before Final Fantasy turned Bahamut into a dragon, it was a fish
Actually a real-world fungus, just heard about it. A fungus that tastes well and all, no ill effects. UNLESS you consume some beverage, even 3 (three) days after eating it. Then you become really sick, pains, vomiting, all the fancy stuff. Was really used to cure alcoholism. May be a joke or to make sure the heroes spend their time focused on the mission.