Hi, I do have some (a bit) of experience with Cobb here in Brazil. As already posted, the materials are locally available, all you have to do its start experimenting the dirt around you and you will be touched, never to stop!
In my area, Minas Gerais, there is plenty of brachiaria grass "capim", the very hard working African immigrant that constantly annoys local governments and is to be found all over.
The deal is simple: watch for roadside mowing (roçada). After the rainy season is really common, but you can always use pretty much any fibrous brown material to start with. Wet down your dirt and step on it.
Good luck.
