The longer lens got rid of the vignetting!
Unfortunately it did nothing for my ability to find my focus, and in the rare occasion I could do that, hold focus for more than a split second. Finally got my tripod out for some of them, which came out a bit better.
1. Yarrow, handheld
2. Yarrow, with tripod
3. Yarrow buds, with tripod
4. Just for comparision, Yarrow with my 55-250mm "macro" at the minimum 3'6 focusing distance (macro my behind)