We have many, many goldenrod plants in this area – they are common everywhere, though when I was very young, my grandfather had an allotment and I remember that he had goldenrod growing around the shed. One of my earliest memories.
Goldenrod are very susceptible to galls. Almost every stem has at least one. These are made by the plant as a result of an insect sting. The resulting gall provides food and shelter to the insect grub. The insect is the goldenrod gall fly.
I noticed a downy woodpecker on the weed stems in my garden, where I usually see chickadees and juncos. Unusual, as woodpeckers aren’t big seed eaters. Then I realized it was eating the gall fly larvae. Once it had gone, I checked out the galls. Every single gall had a large hole in it, much bigger than the exit hole normally made by the fly, when it hatches out the next spring.