oh, well I guess I should explain a little, digging them will work (although the tap root can go down a long ways) if they are accessible where you can dig. I use roundup on mine because they grow up under my roses

and I am afraid of damaging the roots of my bush, plus I can't get in there without getting thorned ... So I just lay on the ground kind of and paint the roundup on, that way they die in place and I don't disturb the other plants. I don't notice these in my lawn so I assume that mowing them over and over eventually causes them to die off. I assume they mature and make seed, but I never let that happen, I hope to eventually be rid of them altogether.