Quoted:
If you didn't plant in a hill be reeeelly careful on digging around the plant. Those suckers will dive straight into that hard pan and it is a beeeeach getting them out without breaking. You might try just digging one or two plants to see how the yield looks. You could dig some now, wait a couple weeks and dig somemore until frost sets in.
Sounds like you are looking over my shoulder.
They are more "hilled" now than when they were planted as the ground bulges beneath them. I remember digging them in my youth in the muck soils of south florida from what I teased my gardening neighbor looked like mayan temple mounds. I think she had the right idea.
Yield seems prettty good, I wouldn't really know what it should be. I am getting well over 10lbs per hill. (15lbs out of last hill, including the weight of a 5 gallon bucket)
I am going to have to string them out till frost since I am short of space to dry and store them. They were planted as an after thought when my MIL asked if I would grow some for her.