Help identifying a snake.

[John e boy]

Hello, I am a new member on this forum. A little about my self; I am a second year Vet tech student with a big interest in Reptile and amphibian anatomy, physiology and medicine. I am the owner of a garter snake that I have had for roughly one year. I bought him/her in a reptile expo when it was a very shy and tiny snake. Upon my graduation I plan to do work in conservation with my local Fish and wildlife dept. Now for my question, I found the snake in the pictures in my front yard. The problem I am having is that I have lived here(Eastern PA) for 13 years and I have never seen one on my lawn. The ones found in the forests near my home don't have the coloration this one has. I am 95% sure it is a garter snake. The only thing that makes me question this is its color, and the size of the head when compared to the length and girth of the body. I would really appreciate if someone with more experience than myself took a look at the photos and told me their thought on it.

Thanks you.