Illinois

The Mazon Creek concretions — Pennsylvanian ferns, Tully monsters, jellyfish, shrimps — come largely from the reclaimed strip-mine spoil of Pit 11 in the Mazonia-Braidwood State Fish and Wildlife Area. The Illinois DNR requires a fossil-collecting day permit, obtainable from the site office or online, and restricts collecting to 1 March through 30 September (outside the waterfowl season). Excavation and collecting for commercial purposes are prohibited; the concretions are for personal collections, and the site asks for a report of finds.

Surface collecting with hand tools is the norm; concretions are picked from the spoil and opened by freeze-thaw at home. The rest of the Mazon Creek area is private (the Braidwood pits owned by the power company, farms along the creek) and requires the owner's permission; the classic creek banks are private too.

Illinois state parks and nature preserves prohibit removal of natural materials; the Illinois State Geological Survey and the Field Museum identify Mazon material and the ESCONI club runs the collecting community. Illinois also has a state ivory law (Ivory Ban Act, 2018) prohibiting sale of elephant and mammoth ivory with limited exceptions.

Verify locally: the current permit form and any daily quantity limit — the site rules have been revised more than once.