Well - the update is that no ambulance was required, so the purple mushrooms (which have turned brown on cooking - how boring!) will be on offer to all who wish this evening.
There's not much chance of poisoning Bee as he won't touch them, but Dragonfly is quite keen. She's always liked mushrooms and, when she was small, she called them 'champions' instead of 'champignons' in French, which seemed quite an appropriate mispronunciation given her enthusiasm for the things. During this phase, Bee was once called a champion for doing something impressive (running? jumping?), but was totally unimpressed as he thought he was being called a mushroom.