Nepeta cataria

Naturalized in North America (meaning, not originally from here but now grows wild).

Very low maintenance, and if you let catnip go to seed, it will pop up again next year. In flowers gardens its greyish leaves make it a compliment brightly coloured flowers.

Well known for its love by cats, and lesser known as a herbal sedative for humans. So drink a Catnip tea before bedtime if you have trouble sleeping.