I ripped mine out, and the rhizomes/tubers were small like yours. Maybe the larger tubers stayed in the ground? I can't find any information online about them having small, non edible tubers, but your plant is definitely Helianthus tuberosus. They sell selections that have been bred to produce larger tubers. If a bunch return in the area where I ripped them out, I'll dig them out and look at the tubers.

Signet, we can't ID a Helianthus based on rhizome alone. If you still have doubts, you'll have to allow one to grow to flowering, and submit photos of the stem, leaves, abaxial and adaxial, the flower face on, and the back of the flower showing the involucre. Lower leaves, and leaves higher up.

On a practical note, Signet, it’s easier for us if you keep follow up questions about the same plant in the original thread. That way people can see the whole story and all the photos in one place. Otherwise the posts drift apart and readers don’t have all the information.

I think it goes with this:

https://www.houzz.com/discussions/6272442/would-appreciate-any-help-to-id-this-plant

Floral_uk I did try that but I think everyone assumed that the id had been made and story over so I started part 2 because I really was confused about these tubers that don't look like images of the tubers shown on Google for JA.