I live in the Presidential neighborhood of Deadwood, so hiking up to White Rocks (elevation 5250 ft) is a common event for me. It is a short hike, but a great workout that rewards you will great views of the area.
My Black Hills, Northeast #751 map shows this as BLM land – so it is open to the public. The easiest way to find it is through Mount Moriah and and follow the signs all the way up to the grave of Seth Bullock. There is a service road for the nearby mobile phone tower. Just follow that up the hill and you’ll see trails heading to the top.
This is just one of the many hiking options in the area.
Enjoy this video of the 360 degree view from the top