What bug is this?

I'm trying to learn more about this bug, I have spent a lot of time in gardens and hadn't noticed it until a few days ago. I have managed to find 5 now. They seem to get about 1 inch long (or slightly shorter) and have 6 legs that are all up by their head. They move quickly and attempt to run. This was found in northwest Washington State in the soil, seems to prefer to be in the top 1 inch of soil, and (maybe coincidentally) found near decaying plant matter. Searching lists of commonly found bugs/insects in gardens so far hasn't turned anything up. Any help is appreciated.