Do you mean Cannas' root as in Canna lilies. I read that in some parts of the world, they are cultivated for food for humans and livestock. What did they taste like? We grow them in flower beds and dig them up every fall. Always have 4 or 5 times what was planted in spring. Never tasted them though.
I did years ago, have a patch of Jerusalem artichokes. Grew them as a favor for my G_Grandfather who loved them. I tried several different ways of making them. None were good and all required beano.
Oddly, I like Beets and turnips, wife loves parsnips, which aren't too common around here. But she makes them in with a brown sugar maple glaze that anybody would like.,
At a meeting a guy trying to do a demonstration about common ideas asked me to name a root vegetable. Of course I guess I do not think like other folks. with no hesitation, I answered with the first root vegetable that popped into my mind, "Rutabaga" The crowd burst out laughing and the speaker was so befuddled that he lost his thoughts and had to be reminded what he was doing. (Of course he was looking for and expected the word carrot) So a few months later when it was my turn to instruct the crowd, I gave them a true false quiz about the history, parentage and events surrounding the Rutabaga. (The farmers market in Syracuse NY has a Rutabaga bowling contest every December. A rutabaga is a natural cross between a cabbage and a turnip and has been known to gardeners for at least 400 years..)