This keeps coming up in my veg patch. I have never left it long enough to see if it flowers but it spreads like wildfire! It's pretty prickly too, so I have to use gloves when getting it out!
looks more like Borage to me, which forget-me-not is in the family of.
I looked up comfrey and wow, yeah, that makes ALOT of sense. People use it as natural fertiliser. There's so much about it online! Seeing as its in my veg patch from the people previously, I guess that's what they were using it for! Well I'm still going to dig it up, because from the sounds of it unless I dig a long long way down, it will keep coming back! So I'm going to dig up what I can and plant it in an area down the end of the garden so it can go wild and I can't experiment with the leaves
Although, most of the pictures I see of comfrey, they don't have spots
Try green alkanet, Pentaglossis sempervirens