Regarding comfrey, one source for several varieties is Richter's Herb
Catalogue. www.richters.com
I make a comfrey and calendula salve which has the property of stopping
muscle cramps.
Comfrey is valuable as a feed for animals, people, and is an excellent bee
plant. There are stories here in Alaska of old timers who would plant a
big garden of comfrey and eat it every day during the growing season- one
local lady lived a fiesty life well into her nineties on this regimen.
(This in the days when almost no greens or vegetables came from Outside.)