This coalified fossil could be a decorticated bark of Prolepidodendron or Lepdidodendropsis from the Upper Devonian New Albany Shale. The New Albany Shale can be found around the southern Indiana and northern Kentucky. Usually when I find this type of fossil I think of it being an Archaeopteris or Callixylon.
I took these pictures at a local fossil study meeting. Thanks to Herb and Bruno for their opinion as to what this might be.