Does anyone know the origin of the keyhole bed concept? It appears in the Designer's Manual (1988), in a drawing called "Gangamma's Mandala" but there is apparently no mention of it in "Permaculture One" (1978). There is a design of a similar shape in a 1982 article by Susun Weed called a c*** garden. Trying to see if either author borrowed the idea from the other, or from somewhere or someone else?
Bill Mollison talks about it in his Permaculture, A Designers’ Manual, as the Gangamma’s Mandala [p.269, picture p. 274]. He took inspiration from Taiwan and the Philippines to design this polycultural garden. Linda Woodrow’s book, The Permaculture Home Garden, seems to give a more detailed approach to this concept, adapted to tempered climates.
At the bottom under Sources
Bill Mollison, Permaculture, A Designers’s Manual, Tahari, 1997
If you search for something like "ancient garden drawings" you get a lot of pics going back hundreds of years that include circular elements with a little path into the middle. Although I think a lot of these are for formal landscape architecture type gardens, not vegetable gardens. Here is a collection of such illustrations: https://www.pinterest.com/nidzalina/ancient-garden-drawings/
Since the keyhole garden is a sensible, intuitive design that uses the most basic of shapes, I'm going to guess that keyhole gardens have been independently "invented" by numerous gardeners since the dawn of agriculture.