It looks most likely to be ripple marks. Here are some references I found:
I would certainly contact this geology professor as he seems knowledgeable in the area.
Of the fossils mentioned here (brachiopods, ostracodes, trilobites, and tentaculitids) it does not match most of these. Only perhaps some ostracod marks.
It definitely looks like it was formed on an old shoreline.
When taking pictures also try to include something for scale. Are there any more edges of this pattern or does it pretty well cover the whole rest of the sample?
Let me know what you find out. I have enjoyed collecting fossils in MD. It has something from every geological period. I have attached a list of MD fossil sites were I collected in 2015.
Let me know what you find out.