Moved into a new house last autumn and thought I had a decent looking lawn. Come this spring and I noticed this dark grass with a large, dark brown seed head emerging. After a bit of reserch I've discovered it's called Field Woodrush. Can't find out how to get rid of it. All the lawn weedkillers I've seen don't seem to mention it and they only seem to treat broad-leaved leaves. Has anyone any ideas?