I found this Hiking in the Buffalo Gap Grasslands today. I know it's only the imprints, but it's on a cool agate. I was so excited I snapped a pic out on my hike. I have a feeling there are lots more like this to find!
Very nice. I have lived in the Black Hills most of my life and really enjoy hunting for rocks and fossils. My yard is full of them. I see you have also caught the rock bug. Best of luck.