I tried to find the best design for a raised bed garden box. My original design
is made of 2x6 untreated pine lunmber, although larger sizes are possible. The ends
are notched half way so that two adjacent pieces overlap. The ends are drilled through
to accept galvanized timber spikes, or just as well, 3/8ths rebar. The later
holds the pieces together and anchors the box when driven sufficiently into the ground.
Making Bill's I formed loops in the rebar, sort of like handles. Alternately, the rebar can be left long and used to attach PVC loops in order to stretch over cover cloth or shade cloth, depending on the season.
I like this design because you can actually make an irregular shaped garden, say following meandering path around your yard, all the while keeping it small enough to work from the edges.