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.
Plant that is likely to produce allergic reactions in almost everybody, even by touch. Usage: medicinal, in very exotic foods, non-lethal traps, disabling opponents (have you ever cut an onion,anyway?), spell components, etc.
A local fungus-breed explodes if hit or fallen upon. If there is any conflict between inteligent enemies,both sides are likely to use it to their advantage.
The old hermit living outside the village is rumoured to have a small rusty tin spoon that seems disturbingly ordinary but in reality is a magic spoon. If someone puts the spoon in their mouth will taste food. It can be any type of food, grilled meats, cheese, strawberry, bread and so on. The real bonus is that the food is real and with enough tastings can fill a hungry belly.