Our yellow woodsorrel doesn't get tall like yours did, but it does spread a lot. And I find it difficult to get out the way that it grows.
I have one of those pink ones in my shade garden. Well, several.
My Mom found it on the side of the road one day while walking and planted it at her house. I think she had three when I dug mine up. It didn't do as well for me (do you grow yours in sun or shade?) and I ended up digging it up its second year (it didn't even bloom for me).
Well, the next year, I found its children all over the garden bed. Needless to say, I left them, but there's too many to count. I don't know how it went from blooming once, to no blooms/being dug out, to spreading all over the garden bed.
