Photo courtesy of David Backlin (taken December 2011)
This sign stack on Missouri 13 north of Osceola is at the south end of a "Michigan Left", rare in Missouri, which is an intersection at which left turns across a divided highway are prohibited, with those turns accommodated at a median turnaround a short distance from the intersection (further explanation at Michigan Highways).
Also note the "pointy" style state outlines (as explained in this comparison).