Weeds are plants that colonize disturbed land effectively. You can see the common weeds where you live by finding a building site. Look at ground that was turned over and has its first growth of plants. Those are weeds. The scent is barely perceptible in the flowers.
Some people describe it as slightly minty.
The blue petals are set in a flat, wide disc. At the center of the blue petals is a ring of yellow and white, soft, slightly sticky structures. Once you, the pollinator, get to the center of the target, the ring is hard to avoid. If you bump against them, they might get stuck to you. The anthers are the pollen-bearing structures that form the ends of the stamens.