Back in 2000, when I was a lowly undergraduate, the warden in charge of our halls called all the resident students to the bar for a meeting. There, he warned us of a terrible health and safety menace. Apparently, near the student village, there lurked a large crop of magic mushrooms. On no account, he informed us, were we to go near the mushrooms located in the field at the top end of the village, nor were we to pick the white ones with the brownish tops on them.