I showed Jeffery P the Jacksboro spillway on his swing through Texas and it was my day to find plants in this otherwise marine site. At least I think that both are plants.
First this piece with mm scale which I'm guessing could be Cordaites or Artisia pith.
Edge view
and close-up
and other side
Next this leaf which I think is one of the seed fern pinnules, also with mm scale