Garden
Bee balm (Monarda didyma, zones 4 to 9) has become a favorite functional perennial of mine. I have used this plant to battle latent weed seed spikes of Canada thistle (Cirsium arvense, zones 3 to 7) with little maintenance. VERY INVASIVE Although this plant is susceptible to powdery mildew, it never really looks bad to me en masse. If it's a bother to you, cut it to the ground and watch it push out new, clean foliage the same year.
Lily turf (Liriope muscari 'Big Blue', zones 5 to 10) has filled the racks of many retail outlets. But the species I find truly effective is Liriope spicata (zones 4 to 10). This plant slowly spreads across the ground plane and creates masses so thick, I have found myself laying in its comfort with my little ones. Go ahead and try it; the plant won't mind in the least! Summer flowers are a bonus with this exceptional plant.
Dead nettle (Lamium purpureum, zones 3 to 8) can spread in dry shade, in rocky outcroppings, under pines, in dense woods and even in some shade. It can be effective at managing erosion, as it spreads from rooting stems. I've seen this low spreader find its way through wood lots and even hold its own against stilt grass (Microstegium vimineum).
Q