Q. Where is there evidence of volcano calderas in Missouri? A. "The St. Francois Mountains is a region of formerly extensive volcanic terrane comprising several calderas, cauldron subsidence structures, ring intrusions, and resurgent cauldrons. Three calderas are recognized: the Taum Sauk, the Butler Hill, and the Hawn Peak [sic]." -- https://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=MOpCAv%3B0 (The term Hawn Peak is used in error, it is actually Hawn Park Caldera. Verified 3/11/2020, Geologic Survey Program, Missouri Geological Survey.)
The St. Francois Mountains are sometimes referred to as The St. Francois Mountains Volcanic Supergroup. A supergroup is defined thusly: "A lithostratigraphic unit composed of several associated groups or of associated formations and groups with significant lithologic features in common." -- Jackson, J.A. and Bates, R.L. (1997) Glossary of Geology. 4th Edition, American Geological Institute, Alexandria, 769 p.
Hughes Mountain, Devil's Honeycomb. Image by By Cliff White, Art Director - Missouri Department of Conservation, Attribution, https://commons.wikimedia.org/w/index.php?curid=6659892