Prof. Anita W.Novinsky from Sao Paulo University is an expert on the subject of the Anusim (Crypto Jews, Coversos) in Brazil. I saw a long interview with her on the Documentary: A Estrela Oculta do Sertão, dealing with the subject of the estimated 120 million Anusim in Brazil. I asked her if she stumbled upon Stars of David in Brazil.
She wrote to me that the star of David is very common in the north east of brazil, by the people in general. (according to the above mentioned documentary most of the anusim are concentrated in this area).
The star of David is used by fishermen, who leave to the sea in a boat, and in the bottom of the boat they print the star of David, to give them luck.
There are anusim who use the star in their chain, and in their homes it appears frequently.
Prof. Anita W.Novinsky referred me for detailled informations in the books of the famous folklorist Luiz Camara Cascudo.