Hi JB,
Memory foam does have the most “chemicals” out of the three main types of foam materials (memory foam, polyfoam, and latex foam) and anecdotally there are probably more people that are sensitive to memory foam than the other types of foam (especially if they have medical conditions such as Multiple Chemical Sensitivities) but for most people memory foam that is either made in North America and/or is CertiPur certified is “safe enough” for their criteria.
You certainly have some good options that will hopefully meet all your criteria either in the Houston area list (that you could test in person) or from one of the online manufacturers that are members of this site that are listed here.
Phoenix