[wbmkk]

I found some of this plant growing nearby and I think it is comfrey.

Am I correct ?

There seem to be wee, tiny hairs on the leaf surface

If it is comfrey, I can take a few pieces and 'grow my own fertiliser'

[BabbyAnn]

yes, that is comfrey - to propagate, you just need a bit of root (or split a crown like a rhubarb)  If it is "wild" as opposed to cultivated, you might be able to find some baby plants around which should give you the clue that  they can readily self seed, and with such a deep tap root, very difficult to eradicate if it grows where you don't want it.  Make sure the bed where you plant it is not going to be needed in the future for other crops or flowers.  Comfrey flowers are bee magnets - my bed of comfrey hums in summer with the hundreds of bumble bees visiting it 

[Trillium]

I second not using wild comfrey in a small area. A friend did and comfrey took over despite their best efforts to remove it. True, bees love it, but who cares when all your wanted plants become swamped in it.

Best to just buy a root or two of Boking 14, the sterile hybrid, and you can propagate from there.