I think this is a weed with my helenium double trouble. Can you help?

These two are the questionable plant



This is the helenium

The stems are different. The mystery has smoothe round stem. The helenium has stripes and a "fin" on the stems
Helenium

Mystery


The base of the two next to each other


The leaves are similar. But not quite the same



Any help appreciated! Thanks in advance

How about, Genus Solidago - Goldenrod

First thing I thought of was Goldenrod when I saw the photos.
Could it be Solidago canadensis?

I think Solidago it is. I will dig it up tomorrow and see if I can sepatate the two

For comparison here's Goldenrod (Solidago canadensis)