We evaluated an assemblage of 235 plant fossil specimens from the well-known Middle Pennsylvanian Mazon Creek locality accessioned into the Paleontology Collections of the North Carolina Museum of Natural Sciences (Raleigh). The specimens are preserved as siderite nodules, common to the Mazon Creek biota. All but three of the specimens were donated by Mr. George Oliver, and were found at a quarry near Joliet in Will County, Illinois. The collection includes pteridosperms, pteridophytes, lycophytes, equisetophytes, cordaites, and specimens of unknown affinities, and includes relatively rare specimens of Codonotheca caudua and Cordaianthus ovata. Forty-four previously unidentified specimens were identified to genus or species. Sixty specimens were previously misidentified and corrections were made. This is a small but noteworthy collection that increases paleobotanical material available for researchers to access.