Many North American pearl mussels produce high-quality pearls. Use of these pearls for jewelry and decorative objects dates back at least 2,000 years, to the ancient Hopewell culture in Ohio. But subsequently, American freshwater pearls went almost unnoticed until the mid-1800s, when several people reported finding spectacular pearls in rivers and streams around the United States. Those discoveries triggered the beginning of large-scale harvesting—first for pearls, later for mother-of-pearl to be used in buttons, and today for shells to produce nuclei for cultured pearls.