We are buying our daughter a new mattress and don?t know where to dispose of the old one. Any suggestions? Thank you 

I'm just guessing but I think if you have Waste Management, they will pick it up from the curb. 

Usually the mattress company will take it away for you? But it you are buying the mattress outright on your own, call your trash company. 

Some won't take them because of the bed bug epidemic.