Typically when I want to get rid of things, I do it when the boys are at school, and make sure it's safely at the bottom of the outside garbage can before they get home. I couldn't do that today as they were home, and, in general, I've grown tired of lying to them about where the missing things are ('I have no idea where that pink plastic top could be'), because of course they always end up wanting them. So I told them: I'm getting rid of this stuff, because these little plastic toys don't last. They take up too much space in our house and in our minds. You don't really play with them anyway. We have so many creative things to play with and enjoy...let's make sure we have enough room for these things. They got it, much to my surprise, though we ended up keeping more than I had intended to.
A friend recently asked me how I manage artwork. Mainly I do it by taking pictures of it and then recycling. Really special things, I keep the original too, in a large plastic container, the contents of which may someday get converted into scrapbooks. The boys also each have their own peg board to display their work and anything else that inspires them. Their boards are a mix of things they've made, found and been given: artwork, cards from friends, magazine tear-outs, photographs, etc. Every few months we take things down for a fresh start.
The boys also have their own shelf in their shared room, and this is another great space for them to display and keep special treasures.