I have considered log edging, Im not Sure I have access to enough wood of a decent thickness. It would look fantastic, and im sure there would be some beneficial properties having decomposing wood in the bed.
I could end up needing 100m+ of edging material to complete my design
You can make an octagon shape instead of a circle.
My husband cut 2x4s to the correct angle for me to use for the joints. The sides are made from fence slats. I thought about making more of a keyhole shape but decided against it mostly because my carpentry skills are pretty poor and I really wanted to just get this done.
Companion Planting Guide by World Permaculture Association