mine's rhubarb crumble
It was not eaten as food until the 18th century.
The stalks are the only part of the rhubarb plant that should be eaten. The leaves contain oxalic acid and are toxic to humans.
When actors are asked to speak unintelligibly in the background of a scene, they often repeat the word "rhubarb" over and over again with different intonations, to make it look like they are having a conversation.