While driving from Windhoek to Etosha National Park, in Namibia, there were lots of vendors at the side of the road holding up mushrooms for sale. Specifically, they were selling the Omajowa mushroom, pronounced omayova, Termitomyces schimperi. In Afrikaans and German they are also referred to as Termitenpilz. They are in the family Agaricales.
Omajowa grows on termite mounds of the species Macrotermes michaelseni. These mushrooms grow across southern Africa, but I think are particularly common in northern Namibia. The mushroom was first described in Ethiopia by Patouillard in 1891.
The mushrooms are very large. The ones I saw were up to 30 cm diameter when fully opened.
They need to be picked quickly once they have emerged, otherwise they get infested by insects and get sand blown into the gills.
[van der Westhuizen and Eicker (1991)](https://doi.org/10.1016/S0254-6299(16%2930986-3) describe the mushroom as having a firm and fleshy pileus, expanding to convex-applanate, with crowded free gills creamy white to pinkish. The spore print is brownish-pink. The emerging mushroom is about the size of a fist. The fully emerged mushroom can be up to 50 cm tall.
The mushrooms emerge after heavy rains, mostly between January and March. The mushrooms are very common around Otjiwarongo and Okahandja.
The name Omajowa is used by both the Herero and Ovambo people.
People from Windhoek often pick up these mushrooms from vendors on the road between Windhoek and Okahandja. The mushrooms have a fleshy texture and a strong nutty taste. The mushrooms can be barbecued as steaks, like portobello mushrooms, or chopped up and fried with lots of butter, salt and pepper then eaten on toast.
The large mushroom in the picture below was being sold for 20 namibian dollars, or about £1.