Univ. of North Carolina, Chapel Hill. Concise textbook for medical students on rotation, or for resident training. Presents a practical, clinical overview of common health problems, including diagnostic approaches and treatment. Previous edition: c1993. Softcover. DNLM: Family Practice.
This book is pretty complete when it comes to topics in family medicine, but (much like family medicine itself) it's kind of superficial and doesn't go into enough depth on the pathophysiology of each condition, how to diagnosis it, how to treat it, etc. It was definitely enough for my med school's departmental clerkship exam (I read the text in its entirety and I aced the exam), but it lacks the thorough explanations that you really need to understand all of the pathology that you encounter in family medicine.
Additionally, since family medicine is largely a lot of preventative medicine and the recommendations about screening, vaccines, etc. are often changing, any textbook is probably not the best source for that kind of information. However, shelf exams are made up of old USMLE step 2 questions, so any questions you might encounter on that exam would probably be sufficiently answered in a relatively recent textbook, like this one.