I know what it is, but the name is slipping me right now, I'm currently trying to look it up.
It's common in landscape beds and hard to control. My theory is that even after you kill off the existing weed, the seed in the area left behind will still germinate.
One section I've tried to control in a bed has taken me 3 years to get to an acceptable situation. Glyph only (no pre-em by HO request).