Identify this weed
It would be a lot easier if you had a photo of the flower or fruit/seed. Identifying on the basis of leaf only (and fall version at that) is difficult. Yes, it could be an Asclepias spp. But it also might be this:
Dennis, there WAS no flower. Don't know how much better evidence I could send you than the closeup of the plant and th view of the patch.
Below is a panoramic of the North field (weed in question) and the South field (where the obvious traditional milkweed is).
Is it possible it could be immature milkweed?
It is not unusual for common milkweed (and that would be my guess since you have it in an adjacent field and it reseeds prolifically) not to bloom on first year (or even second year) plants.