Reddit mentions of The Spears of Twilight: Life and Death in the Amazon Jungle

No problem, it is a fascinating topic. I don't know what to suggest, there's way way too many books.
Really top of my head, any anthropologist here will probably crucify me for forgetting something, I would suggest the following :

• Mead - Sex and Temperement
  
  
• Levi-Strauss - Savage Mind
  
  
• Descola - Spears of Twilight
  
  
• Mauss- The Gift
  
  
• Malinowski - Argonauts of the Pacific
  
  
• Clastres - Society against the State
  
  
• Levi-Strauss - Tristes Tropiques
  
  Some are more or less technical and harder to read without a background, I remember Malinoswki, Descola and Mead to be fairly easy to read. Tristes Tropiques is also very easy, it's like a novel. Mauss, Clastres and Savage Mind can be a bit more "advanced" but they are very readable.
  
  EDIT : Fun fact about something similar to cargo cult. Some tribes, don't remember if it's in Africa or Oceania, value foreign objects as possessing supernatural powers. As such, they cover their shields (which are absolutely amazing) with stickers, such as beer brands. The anthropoligist that told me this said that he tried to tell them that they are ruining the beautiful shield and they just thought he was an idiot, the shield looked much nicer with the stickers.

Still not an academic-academic source, but I'm currently reading Philippe Descola's The Spears of Twilight: Life and Death in the Amazon Jungle (1998). what might be of interest to you is his account of how he finally managed to gain access to a group of Jivaro Indians of Amazonian Ecuador. Plus it's a marvellous read in its own right, anyway!