Smile at your DH real sweetly and take as much of the comfrey as you can get. Mix the leaves with newspaper, shredded tree leaves and some soil, you can soon have the most gorgeous soil possible. See "lasagna" for one method which is fast and reliable. The comfrey roots can be dug up and also composted, although I would chop them first. If you want to take over the area where it's growing, use the lasagna method with the bottom-most paper layer being at least 1/2" thick, and the lasagna layers should be not less than 15" tall.

Get in touch with an organic or herb garden club & offer it to them if they'll come get it.

I gave away a number of comfrey plants to someone who took them to his organic club to sell at their fundraiser!