Rhodri feels up the tree for some sort of hidden door.
If that doesn't work, he'll try to climb the tree or nearby trees to look through the window.
Oh! And he'll use some grass to bind a stick and rock together, creating a tool that can bash things. Or as a crude axe. Or pickaxe, if sharp enough. Or cudgel... It's a rock attached to a stick, it has a lot of uses if you have enough imagination.