what kind of spider is this? located in central oklahoma?

crab spider its harmless

It is a crab spider, but not one of the 'running crab spiders'. This is one of the standard 'sit-and-wait' hunters that operate on the ground or on stems, branches or trunks of plants. I'm not sure which one this is, but it looks very distinctive, so it should be pretty easy to ID - try submitting the photo to Bug Guide for ID by their experts: http://bugguide.net/node/view/6/bgimage
You can always poke around in the Bug Guide archives - I'd start with the Xysticus spiders, but that's just a guess: http://bugguide.net/node/view/6750/bgimage
In any event, all known Crab Spiders are completely harmless, so there's that.

Looks like a crab spider. They're fast little buggers but good to have around because they eat small bugs.

This is a very young running crab spider, and quite harmless. (looks like male)
http://bugguide.net/node/view/682189/bgpage

Could be a wolf spider.