Craigslist is your best place
Full circle is the best option also consider checking the free section of craigslist every useful items there.
There are many programs probably in your area I want to say there's a charitable organization called the full circle and there's also a Montgomery County program that receives donations and your caseworker can give you a letter where you can get some free things. I don't know where you're located so you'll have to ask your caseworker for advice or if you have a computer you can Google charities in your area. I believe that Salvation Army and other places like them do not give away anything for free because it's a matter of rule and possibly law
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