I live in Westport, Connecticut, United States, and want to sell my bed.
As a consumer, am I allowed to sell my mattress, even though I've used it?
If so, are there any restrictions/regulations I must adhere to?
At the state level, the regulations that must be adhered to are laid out in Sections 21a-231 through 21a-236 of CT Statutes. In general, it appears that mattresses have to be sterilized before being resold in a store (and clearly labeled as such), but the law specifically exempts private person-to-person sales from this requirement.
(g) No person shall sell any secondhand bedding or filling material unless (1) it has been sterilized or sanitized and has a tag bearing the secondhand dealer's license number and the permit number of the person performing the sterilization or sanitation, or (2) in the case of secondhand bedding or filling material manufactured at least twenty-five but no more than fifty years prior to the date on which such secondhand bedding or filling material is offered for sale, the secondhand dealer notifies the consumer, in writing, that such secondhand bedding or filling material has not been sterilized or sanitized.
(o) Nothing in this chapter shall apply to automotive upholstery, private sales from the home of the owner direct to a consumer, bedding offered for sale at public auction in the home of the owner, and bedding manufactured at least fifty years prior to the date on which the bedding is offered for sale.
It is possible that there are local laws in Westport imposing additional rules, though my gut instinct is that such a law would be unusual at the local level. Local ordinances about the disposal of mattresses are more common, so if you don't find a buyer, you may need to look in to those.