LEGO has an initiative to help with environmental sustainability in the form of reuse of their bricks. Their Replay program encourages you to donate the no-longer-used bricks to children in need.
LEGO Replay is a simple-to-use platform that allows you to pass forward your much-loved LEGO bricks and share the power of play with kids in need. When children play with your donated LEGO bricks, it helps them learn to problem solve, collaborate, and think creatively. With LEGO Replay, worlds of play can be rebuilt and reimagined many times over helping to inspire the builders of tomorrow.
You simply print out a packing label and ship the bricks.
The program seems like a great idea, as LEGO bricks tend to hold up well over time. Some of our collection is from when my brother and I were kids. Sadly, neither of my boys still play with their LEGO sets, so I am tempted to encourage the donation of these toys to those who might appreciate and use them.