Unusual looking snake
Thank you for your question. The snake in your photograph is a Northern brownsnake, scientific name (Storeria dekayi dekayi). It is a non-venomous species.
This species is found throughout most of the eastern United States. It is often found under cover such as mulch, pine needles, logs, rocks and boards. They are also frequently found in flower beds. They feed primarily on earthworms, slugs and snails. They give birth to live young in the summer. Litter sizes range from 4 - 25 young.
Typical length is 9 - 11 inches, but maximum length can be approximately 18 inches.
This species rarely attempts to bite, and they're so small that it's tough for them to bite a human if they tried. The snake in your photograph is flattening its body to make itself appear larger in an attempt to intimidate you.
Here is a link to the PA Herp website's page for this species:
Here is an excellent field guide for snakes in your area:
Gibbons, Whit. (2017). Snakes Of The Eastern United States. Athens: University of Georgia Press.
I hope this answers your question, and thank you for contacting Ask an Expert.