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.
As you emerge from the shop in the alleyway, not-too-distant clanging and stamping makes you wary. Further investigation reveals a massive Balgrian protest march flooding the main street, banners roaring about the inhuman conditions in which this ethnic group is forced to live. City guards stand helplessly by, beating up the odd protestor, but unable to hold back the flow. Onlookers throw vegetables at the Balgrians, and shout abuse.