One of the central conflicts in The Things They Carried is the author's internal struggle with the nature of truth as he grapples with his wartime experiences. Throughout the book, he tells stories about what happened to him and his fellow soldiers and frequently changes the version of events. His conflict is in dealing with the effects of the Vietnam war and helping the reader understand that truth is not always factual. Sometimes a story truth is truer than reality.
If this is an assignment for your English class, I am happy to assist you with it. This is one of my all time favorite books!