Shipping cost/effort makes this extremely not worth it for anywhere outside your local metro area where you can do in-person pickup. There are a good number of “Buy Nothing” groups scattered around the states. They mostly organize on facebook unfortunately. If you hook into your local anarchist community they almost certainly have some large signal group chats devoted to things like this. The anarchists are much more about trading of labor instead of just being a place to dump your old shit (trying to avoid the standard trap of mutual aid collapsing into charity) so there will be things like if you post your old stuff you will ask someone to cook you a meal in exchange for it. Sometimes this turns out to be much more trouble than just giving it away but it is what it is.