Digging the Chesapeake and Delaware Canal in the late 1820s cut into Cretaceous sea beds, and the dredge spoil piled along its banks has fed collectors ever since. The Delaware Geological Survey calls the canal the best fossil ground in the state and points to the spoil near St. Georges and at the foundation of the Reedy Point Bridge. The prize is Belemnitella americana, the bullet-shaped guard of an extinct squid relative and the state fossil, alongside big oyster and clam shells, most of them internal moulds, and the odd fish or reptile tooth. The canal lands are under the Army Corps of Engineers, which allows small-scale collecting for private collections; selling what you find breaks federal law. Many older piles are grown over and access changes as the Corps works the canal, so check before you go.
Belemnites, oysters and clams, fish and reptile teeth · Late Cretaceous
Open to the public for collecting, and what you find is yours to keep. Check the posted rules before you start: they can change with the season and the landowner.
Other places on the map within a couple of hours.