These I have collected in Northeast Ohio.
The first is a siltstone, and the second is a sandstone. Both are sedimentary rocks formed by hardening of sediments. Mud or silt in the first rock, and sand in the second rock.
The layering in the siltstone can be caused by different minerals in the darker layers (maybe more iron-bearing minerals). The holes in the sandstone are characteristic of weathering in sandstones.