Arkansas is like the rest of the Bible belt... there are a lot more people who stay closeted there. However, there are quite a few poly peeps in that state, if OkCupid is any kind of accurate gauge. At this time, I am not aware of an active Arkansas poly group meet up...but that doesn't mean much since I am not looking for one.
There did used to be a meetup group for poly folk in Arkansas/Missouri but it has fizzled out due to a sad lack of attendance. I don't know where in Arkansas you are but rumor has it that Eureka Springs is the hub of progressive thinking folk for the state.