Ah yep, Northern Brown Snake. I found one a year or so ago, and having lived in the area all my life and never having seen one, I was rather interested myself. Mine was only 9" long when I found it, and apparently that's their normal size range. Not a monster of a snake like a black rat snake would be.
They're related to garters and eat the same type of food. But their passion I found out is slugs. I kept mine for a month or so till the novelty of bug hunting got old and then re-released it back where I found it down by a creek running through the cow pasture.
Curiously, they're a live-bearer like garters as well. The one I had was a very docile snake that didn't mind being handled.
Nelly:
And considering the time of year, I wouldn't rule out that it wasn't pregnant. Like I said, they're live-bearers, and perhaps the signature traits of gravidity in egg laying snakes is significantly different in a live-bearer. Perhaps someone who owns garters and has been witness to their reproduction could shed some light. But I agree, the area of the body that houses the reproductive system does look a bit more plump than everywhere else.
Are you guys going to return it to the wild? I didn't have the heart to keep mine any longer than a month, it just seemed like a wild spirit caged up. =(