Silphium perfoliatum, a U.S. native wildflower and member of the Aster family, gets its common name, Cup Plant, from the fact that the large, rough leaves are joined around the thick square stem, forming a cup that can hold water.  I like that idea very much.  Cup Plant grows from four to ten feet tall, so it may need staking in a wind storm, and I wouldn't advise planting it on a slope.  The sunflower-like yellow flowers of this interesting perennial plant almost seem an afterthought, but they will provide color to your garden from early to mid-summer. Cup Plant likes full sun/partial shade and moist, loamy soil.  Zones  3-8.  Quarts.  (Photo by Paul Henjum is from Wiki Commons and is in the public domain.)