Let them go to seed and plant the seeds. Cutting that deep tap root usually kills them. I scattered plantain seeds at the end of last summer and they are coming up everywhere.
Discussion
Oh, good to know! I picked a tiny little "pod" thing on one of them, but it just looked sort of puffy. Will the seeds form in those eventually?
Seed stalks will form as the plant matures. You should be able to see the seeds. I let mine sit until they were nice and dry. The chickens started picking seeds off the stalks. 
