39° 35' 33.7" N 84° 46' 04.1" W (WGS84) (Google Maps)

Hueston Woods State Park (Ohio DNR)

Nice Ordovician fossils can be found in limestone at Hueston Woods State Park. Fossil collecting is allowed in two areas within the park (see the park map, link below). The southern area seems to only offer float within a stream bed; however, there are good outcrops along a stream bed at the northern area. Though I did not have much time to spend at this locality, I did find some very nice brachiopod fossils. A more diligent search could turn up other interesting invertebrate fossils, including possible trilobites.

UPDATE (September 2016): On my second visit to this site, I found a lot of isolated, whole brachiopod fossils that had weathered out of these limey mudstones/muddy limestones. Pictures below.

Map of Hueston Woods State Park