Tami I think the seeds would still be viable after a freeze, after all that is the normal propagation. Your dog is smart or well advised. I looked up the medical properties of goldenrod and found it acts as a diuretic, meaning it flushes water from the body by increasing urine output. So it would help her flush her body of any toxins she may have digested. There are several other medical benefits listed in this article below.
http://www.gardensablaze.com/H...
I doubt that there would be many seeds remaining in the dried blooms you found but if you want to collect them and send I could get a start to harvest again in the fall and spread out for the next year. The one plant I had I can no longer find in the brambles.
