http://www.eattheweeds.com/can...
I've added the tubers to soup when I didn't have any taters... they weren't bad tasting.
Around here, they grow easily from seed, and will grow just as readily in a shade garden as in the full sun.
Canna do appreciate being planted in a decent garden bed with deep loose soil.. If you dig a small hole in a hard packed area... you are unlikely to achieve the results you are hoping for...
If given the care that you would give any other garden plant, they sometimes grow a lot more aggressively than many people are prepared for... Be warned... when they drop those seed, they can spread pretty fiercely... especially given plenty of moisture...
I planted them in a ditch as an erosion control measure, and they performed admirably... unfortunately, the home owners weren't as pleased with them as I was!