Nesting in this piece of electrical utility equipment called a "service entrance cap." I've seen both House Sparrows and European Starlings compete for these nesting sites, but I have never seen any other species try to use them. It just doesn't seem right to me that this widespread standard piece of equipment is giving safe homes to invasive species. I might start cataloging every instance of this that I come across.
Flower about the diameter of a pencil eraser.