She may be an Easter egger, or she may simply be a mixed breed bird. You'll know for sure when they start laying---blue or green eggs get the EE label, brown/tan get the barnyard mix.
She's an Easter Egger, not a true Araucana, which are relatively rare and expensive, have tailless rumps, and are not sold by US hatcheries, although the hatcheries frequently market their Easter Eggers are Araucanas or Ameraucanas (frequently misspelled as Americana or Americauna). If you're not familiar with the difference between Araucanas, Ameraucanas, and Easter Eggers, there is a good article at http://www.the-chicken-chick.com/2011/09/ameraucana-easter-egger-or-araucana.html explaining the difference.