See photo of yard and close up of weeds that are taking over my grass. they...
This is Pennsylvania smartweed. It is an annual. Here's a link to info on our website: http://extension.umd.edu/hgic/smartweed
When you thicken up your turf, this weed will not be able to compete. Seed your lawn in late August-early fall.
Pull the flowers so it cannot reseed in beds.