So in garden terms it is a net cloche!
I would have thought these were quite easy to make with some fence wire and some mesh or fleece.
Two hoops of fence wire tied at right angles to each other then laced through preformed eyes which would be formed along the diagonals of a square piece of mesh.
The wires would then be pushed into the soil up to the hem of the net.
Voila a veg (food) umbrella