Might be a fun thing to do with youth. DIY garden plant markers - check out the wood burning kit
Even if you have a small backyard (or no yard at all), you can still grow a DIY herb garden full of tasty plants like basil, cilantro, rosemary, and more. /twotwentyone/ shows you how.
Bug House- Use old bricks and roof panels lying around and build an insect palace in your gardens