No need for trade with me after your past generosities, but if you'll send me a PM on Monday (because I can't do it tomorrow, and otherwise I will forget) I'll run out and dig up some wild roots for you and take them straight to the post office. They are all over beside my dog walking trail this year.
Honestly I have not had good luck propagating these by any method. Seeds are iffy, and when I've tried to dig them, the root (more like, the underground stem) just goes on and on forever. But I did successfully get one growing in a pot last year by digging up a wild one, getting about 18 inches of underground root before my shovel severed it from whatever lies beneath. It grew well until the fritillary butterflies found it and dropped enough caterpillar eggs to devour it entire. It didn't come back this year.
I do have one that volunteered in one of my tire planters last year, and has entirely taken the thing over this year, burying the Juliette tomato plant that I tried to plant there.
I have heard rumors that there's a tuber if you dig deep enough, but I've never found one.
I haven't tried root cuttings per se, but it might work, worth a try anyway! I'll dig you as much root as practical, and you can play with it however you like.