There is a soy-based foam mattress manufactured by the Carolina Mattress Guild. The mattress is comparable in warranty to the major manufacturers and comes in various sizes and degrees of comfort. I personally purchased one after trying the major brand names and finding this soy-based foam mattress equal in comfort.
The bad news is they are located in North Carolina and I see that would be geographically difficult from Arkansas, but contact them and see if it works for you. After all, we spend about 221,920 hours sleeping in our lifetime; it might as well be comfortable.
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You should also read Mary Cordaro's Ask A Pro Q&A, "What do you think of memory foam mattresses and toppers? Are they safe?"