This is actually a legitimate question, and in fact from what I've read, it does work with many plants. Blackberries and raspberries both can be cloned from roots. Weeds you pull from your garden or planter often grow back because of leftover roots in the soil. Some plants can even clone from leaves themselves. I think you should try it, to be honest, since I'm quite curious. I've never done it, but from what I read, you just take 3-4 inches of root and plant it vertically in soil, with the cut end at the top, just under the surface. And much like seedlings, keep them away from a lot of light until they've sprouted.
No promises, however. I think perennials are really the ones that are capable of doing this more than other types, which cannabis is not, but I still say go for it...it will be obvious pretty fast whether or not it's working