(Revised 25 Nov 2017)
I have a pink perennial sweet pea that comes with the house. I consider it a weed, and is very difficult to remove because of the deep and tough roots.
This is a beautiful well behaved Lathyrus. It make a good woodland plant with its neat compact habit and beautiful spring flowers. I believe it is more common to have the purple flower Lathyrus vernus in the garden. The one I have is a pretty soft pink. I have it for a number of years. It only gave me a couple of self-sown seedlings so far.