Things that are still usable should NEVER be thrown away! There is always someone who needs it.
Someone NEEDS YOUR CLUTTER! It's easy to 'let it go' when you know it is going to someone who wants/needs it. AND they come and collect it from you - so easy, no effort - all you have to do is put a FREE message on FREEGLE! (And you get to meet lovely, like-minded people!)
Also, landfill is a dreadful thing. I'm sure it will one day 'come back to bite us'!