Re Neuroscience and Brain/Nervous System I like Liqun Luo's Textbook that I mentioned above. I don't know much about immune system books unfortunately.
Concerning memory and smell, you'll most likely find information in the "popular science" category. Personally I am skeptical about the often-touted "special link" between smell and memory. I don't believe that this link is any more special than the one between vision and memory.
You could also look at Paolo Pelosi's "On The Scent" for a book on the sense of smell aimed at a scientifically keen lay audience.
Concerning memory and smell, you'll most likely find information in the "popular science" category. Personally I am skeptical about the often-touted "special link" between smell and memory. I don't believe that this link is any more special than the one between vision and memory.
You could also look at Paolo Pelosi's "On The Scent" for a book on the sense of smell aimed at a scientifically keen lay audience.