Despite being banned for sale in Australia, herbalists still hold comfrey in high esteem. Historically comfrey was used for a myriad of health issues, speed up healing of broken bones, wound healing, varicose veins, good for your cartilage tendons and muscles. It was as well used for cancer, indigestion, hernia, high blood pressure and much more. The reason for it's ban are PA's which were found in the plants. More on the discussion about comfrey in my blog post: Comfrey - panacea or deadly poison?
Comfrey is regarded as safe to use topically in salves poultices, ant-wrinkle creams and more.
The plant I sell here is the real common comfrey S. officinale. Many comfrey plants sold as the official form are mislabeled and in reality the Russian comfrey S x uplandicum, which contains much more of the discussed PA's than the common comfrey. There is some debate weather or not the leaves of the common comfrey contain PA's at all. In all cases, the roots contain much more of the toxin than the leaves.
Comfrey dies down in winter, and yes the common comfrey sets seeds and may self seed. Comfrey likes sun or part shade a bit of moisture and compost, but I found it will grow everywhere.