The Tallgrass Prairie National Preserve in Kansas is operated by the National Park Service, but owned by The Nature Conservancy in an arrangement that maintains private ownership of the land while ensuring public access and benefit. I've been here several times.
I'll be first hiking the bottomlands trail on the south side of the preserve and then the higher prairie trail to the north.
This is Fox Creek.
Bison are on the land, but were only barely visible when I was there.
You could hike across the open prairie, but frankly, it's easier to stay on the trail.