Hi 3blm,
The first place I would start is post #1 here and the information it links to. This will give you all the information you need and the steps that will lead to the best possible choices. It will also help you eliminate most of the worst quality/value choices so you don’t have to spend any time testing them (such as the Serta and the Tempurpedic).
Before deciding whether a mattress is green I would probably want to know how you are defining it. Most of the green claims about mattresses are actually just “greenwashing” anyway. There is more about this in post #4 here along with post #2 here and the post it links to as well. If a mattress has any polyfoam (including soy foam or any other “plant based foam” or memory foam) then it isn’t green anyway. I would also keep in mind that green and natural are two completely different things. One is about how much the construction of the mattress affects the environment and its carbon footprint from the beginning to the end of its life and the other is about where the materials come from and whether they are sourced in nature or manmade. These are also both very different from “safety” or “toxicity” issues which in turn are very different from organic issues and claims. All of these may be loosely connected but are very different things.
As you will read in the first post I linked … my recommendations are generally towards smaller independent manufacturers that are sold either factory direct or through better sleep shops. My other recommendation is to buy a mattress based on the materials that are in it rather than based on brand. This is the only way to make meaningful quality and value comparisons between mattresses.
The better options and possibilities that i’m aware of in the Chattanooga area are in post #2 here.
Keep in mind as well that no matter where you buy a mattress that it’s important to know the quality details of every layer of a mattress before you buy it. the better manufacturers or retailers will be familiar with these and help to “educate” you about the differences in the materials in the mattress but if they don’t know and you’re unsure you can always list all the layers here and I can help you translate what they are.
Hope this helps
Phoenix