Zoey, here's the promised weed picture (finally!).
I think this might be the one you have. It's oenothera, the one Kathy guessed yours might be.
Here's the root.
This is the "tame" oenothera (evening primrose...I think this one is cinaeus, but I'm not sure). It spreads quite rapidly and can sometimes become invasive. However, it's very easy to pull, and easy to give away too, because it's so bright and pretty. I have it all over the place and move it around often.
It does well here by the back door, where not much else will grow because the rain drops straight down from the high peak of the roof. There's no gutter...too high up. My husband refuses to mess with anything that high! I don't blame him.
hello...here's a little surprise! I wonder will there be kitten pictures popping up in every post?
I'll try to control myself :) 
