Mysterious Backyard Visitor in Union County, New Jersey!

After 4+ years of work to make my yard more wildlife-friendly, I found my very first snake! I'm very excited about my new friend, but I haven't been able to identify him using the usual sources. I am hoping you can help. Note that there is a second pic with a yardstick for scale. Some info:

\- It stayed perfectly still until we tried to pick it up with a branch to move it. We thought it was dead at first, but then it sprinted into the raspberry patch. (I have video of it moving if it will help.)

\- There is no water source in the yard, but there is a creek across the street, maybe 50 yards away.

\- It was in the middle of the lawn (aka weed patch), but there is plenty of cover nearby, including logs, a brush pile, a rock pile, and the aforementioned raspberry patch.

Thanks, everybody!