San Francisco - Fayetteville/Northwest Arkansas (XNA) $88+ tax round trip on American
Looks like you need to travel outbound on a Saturday, with departures mostly in September. Use AA.com or Travelocity and choose the "flexible dates" option.

Having visited Arkansas recently, I can attest to the natural beauty of the region. This makes for a great couple days visit to escape the buzz of the city and relax in the great outdoors.
The Clinton Library isn't to far from here either.

UPDATE: Fare gone!