There isn’t any agreement between OU and Arkansas with the State of Texas, but some out-of-state schools have made it very attractive to leave Texas for an education…
For certain majors and degrees at OU, the out-of-state portion of tuition is waived. http://www.ou.edu/content/admissions/affordability/academic-common-market.html
There are also other non-resident scholarships at OU.
http://www.ou.edu/content/dam/recruitment/scholarships/ScholDescription_15.16_nonres.pdf
Arkansas offers a very good scholarship program for residents of certain states, including Texas.
http://scholarships.uark.edu/nrta/index.php
That being said, both schools offer some great scholarship options for out-of-state students beyond what I have posted above.