The people who lived in our house before us kept a garden in the yard. Tammy and I are both pretty clueless about how to grow a garden. To us, it was just a big pile of dirt (or mud when it rained). His playhouse (which we found on Craigslist) was in another part of the yard. We decided to re-purpose the garden into his play area. We spread out some of the material you put under a mulch bed and added some rubber mulch. That, along with 3 bags of sand in his sandbox, and he was a pretty happy camper.
At one point, he was downstairs watching TV. I looked over a moment later and he was gone. He had went right back to his sandbox with his “blanky” in hand.