I did flat-veg-patch when I was young.

We've got raised beds here. All we did was have the farmer plough the field where we wanted the veg patch, and then just put the soil from the paths on top of the beds [so no proper retaining boards] and its brill! Haven't bug anything and the soil is friable without having been dug etc. (soil is clay and nothing special)

Mine go N-S for what it's worth ...