Here’s a way to join two pieces of wood without visible hardware or nails by using oval wooden biscuits. With a biscuit cutter, plow out a recess in each surface to be joined that will receive the biscuit. Generously apply a water-based glue to the biscuit so that it swells to fill the recess. Now, join both pieces of wood together and clamp until dry.

For more on woodworking, consider:

How To: Make a Mortise-and-Tenon Joint
Bob Vila Radio: Woodworking Tips
7 Essential Woodworking Tools