I have never grown a Canna Lily, though sometimes seeing them growing brings to mind part of a day one fall I spent hosing down rhizomes at Brooklyn Botanic in preparation for their winter storage.
I say what I don't know about Cannas could likely fill books because just by googling around for a bit this afternoon I have learned this plant has been cultivated for thousands of years, a species was long used for food, its seeds are used in musical instruments, and it has gone in and out of fashion it seems since the Victorian Era.
All the things I don't know yet but might discover are just another reason I love gardening and plants so much and maybe even the best reason.