My SO and her dogs live here. Yes, I know there are some snakes that are not venomous or dangerous. This one had a pointed head and we both almost stepped on it. Within 6 feet of the last one(rattler) a few weeks back. So, he met his demise. I will continue to learn to recognize species.
Don't beat yourself up about it. It was a snake and not like it is doomed to extinction. I've killed many since I was a kid and today they are still here. If it runs away when I see it, I let it go. If it is in my yard, coils up and rares back like it will strike me, it will meet Mr. Hoe.