Here is something I did this past late Spring, and early Summer:
There isn't much Cohosh growing natural up in my 'seng planting area, but there are some nice patches here locally. I had some local permissions, so on occasion, I would dig a couple and pot them for transplant. I took the whole plant, root (with a good clump of surrounding soil) and all, and transported 'em up to my 'seng planting area, whereupon I set them back out. I quit doing this right before they went to seed, but by late June, or very early July, I had transplanted about 15 nice mature plants. Hopefully, they will survive up in and around my 'seng beds. If they look like they're gonna make it, I'll do the same this coming season.
I was just thinking that if you knew of any patches along some of your travels, maybe you could do the same.
Also, from some of these local patches, I'll try and remember to collect some seed for you.