College students and young families are always looking for cheap or free furnishings. If your mattress is in good condition, spread the word among friends and family, or place an ad online or in the newspaper. People are usually happy to pick up an item you no longer have use for, especially when you're giving it away.
If you're ordering a new mattress, inquire whether the store will pick up your old mattress on delivery day. Stores that sell new mattresses know that customers are hard-pressed when it comes to getting rid of an old one, and many offer this service free of charge or for a reasonable fee. While your mattress might ultimately end up in the landfill, some mattress stores might donate it for you, or possibly even recycle it for parts. Metal mattress springs, wood frames, cotton and foam are all recyclable once a mattress is deconstructed.
Most thrift stores accept donated mattresses, as long as they're in good condition. You might also contact a crisis center, homeless shelter or halfway house and ask about donating your mattress. Since these types of charitable organizations operate with sparse resources, they might desperately need additional beds, and might not have the same strict standards as thrift and secondhand stores. As long as your mattress is free of obvious stains and odors, you should have no trouble donating it.
When your mattress has seen better days, it might be time to send it to the dump. A mattress that no longer provides support, is mildewed or severely stained won't provide a healthy night's sleep for anyone, and will likely be refused by thrift stores and charitable groups. If you have a suitable vehicle for transporting it, you could take your retired bed straight to the dump and pay to dispose of it. If not, most municipalities schedule free curbside pick-up of large items once or twice per year.