A hillside behind the high school sports field in Fossil, Oregon, found when the school’s foundation was dug in 1949. Drop the small fee in the box, take a trowel or one of the public shovels, and split the shale: the finds are leaves and twigs of the trees that lined the streams 33 million years ago, with the odd insect, salamander or small fish. The John Day Fossil Beds down the road allow no collecting at all; what you split here goes home with you. Spring and fall are kindest, since the hill has little shade in summer.
Leaves and twigs, rare insects and fish · Oligocene, ~33 mya
A commercial or managed site. You pay for access, and what you turn up is yours. Book ahead where the site asks for it.
Other places on the map within a couple of hours.