Read the article, grab a field guide, and step outside your front door. The green allies you've been seeking are wondering what took you so long. Make sure you have permission from the property owner, or are aware of the park regulations in your area. In general, it is helpful to know that fruits and seeds collect fewer toxins than leaves and stems, which in turn collect fewer toxins than roots. You've seen this plant even if you weren't aware of it.
Mugwort takes over parking lots, colonizes unweeded areas of the park, pokes through fences.
It is only a few inches high in early spring, up to six feet by the time it goes to seed in the fall, but at any time of year you will know it by its silvery white undersides that are a bright contrast to its green topsides, and its unique, spicy, musty fragrance when its leaves are crushed. Here is a botanical identification guide. Artemisia vulgaris is a tall-growing herbaceous perennial frequently rising 3 feet or more in height, which spreads both by rhizome and seed. The stalked leaves are dark green on the upper surface, lower surface greyish-white. Leaves are entire or once or twice pinnately lobed, the segments being lance shaped and pointed.