Usually, I associate the brown/tan/reddish chert like rock with the Devonian period and the grey-white like rock with the Silurian period.
This first image the pygidium shows signs of being a forked posterior. A Devonian trilobite that had a forked posterior was the Coronura. The cephalon looks pointed so maybe this is a Silurian Trimerus.
Here is a closer view of the cephalon shown in the last picture. Again it might be a Trimerus.
This rock looks to be Devonian and this pygidium looks worn. The apparent point at the end of the pygidium could be a Trimerus or Dalmanites?