Wash it well. It must be completely clean and free of all foreign matter. It must be dried well, and have NO mold. I would be sure to keep a fan on it as it dries to carry away moisture. I wouldn't dig it before the seeds drop in the early summer.
I've dug couple of pounds this year while out digging seng. I keep hearing about people finding big patches of it and all I ever find is a little here and there. I'm assuming that it has been dug before. Would like to know if anyone buys it in Tn tho. I dug sum today that had roots as big as my thumb! Any info would b much appreciated!