My favorite nursery these days is Silver Heights Farm near my house upstate. They specialize in all kinds of vegetables and herbs: dozens of dozens of rare tomato and pepper seedlings, 14 or so varieties of thyme, a whole row of different basils, Italian greens like puntarelle and also unusual old-fashioned things like lovage, sweet cicely, woad, and comfrey (what I'm holding above).
If you are in Sullivan County on a day they are open (check their website here), then be sure to stop by. You'll be like a kid in a candy store. They also sell at the Union Square Greenmarket on Wednesday and Saturdays and the Callicoon Green Market on Sundays.
This is what my comfrey will look like later in the season. Some people think it is weedy (it is) but what a beauty. It reminds me of an eccentric country woman who used to come stay with us when I was a kid and my parents were out of town. She was what we called a health food nut back in the day. I loved all the witchy herbs she grew in her garden and the concoctions and teas she drank every morning. She made comfrey tea religiously which I now hear is not recommended.
Comfrey (Symphytum officinale) by Karl Blossfeldt