Hello Clydia, et al,
Sorry for the delay, I will do my best to assist you in your questions. I would point out that Wayne's links are an excellent place to start learning...Do be warned...that much of what many (not all) are doing is on there own DIY stuff and experimenting so really compare advice and try to find the commonalities of each recommendation in "means, methods, and materials."
So to your question:
Clydia wrote: I want to know if there is anything in the cob that I might not be able to find here in Brazil.
YES you can find everything you need to make "cobb." In every location...that is the question? So, in most areas of Brazil, you can probably find or adapt the resources available to manufacture Cobb. The base is a clay, sand, and a fiber. The soils in your area that you will be building is your starting point. You must check these for suitability and there are countless online sources, books, videos, etc that will show you these methods.
At this juncture, the other key element that I can share, which you may find useful is to perform your "web searches" in the primary language of Brazil...Portuguese. So I would have started my search with "clay architecture" which is..."argila arquitetura" and from there looked for vernacular forms.
Here is another link that you may find helpful:
Arquitetura de Terra
Taipa is a vernacular form of Cobb in Brazil, and many architects there are turning to a more modern version called "taipa de pilão." As I often tell students..."look to the vernacular forms" of a style or modality and this will often lead you to the best system to use for a given area. Adobe too, is a common practice in Brazil.
Hope this all helps and gets you moving forward...

...I will do my best to answer further questions.
Regards,
j