Nearly everyone has important memories from their childhoods that they recall with great detail due to their significance. However, most of us fail to remember the majority of our memories from our early childhood. For example, try to think of your earliest memory. Difficult isn't it? The explanation for our failure to remember much of our childhood is called childhood amnesia. For example, I often have a hard time remembering things from my childhood that one would assume to be extremely significant, such as the personalities of deceased relatives, the layout of my old house, or even the names of my closest kindergarten friends.
There is also the phenomenon of false memories, and this is often highly correlated with early childhood "memories". These false memories are memories of things that never happened, but that we believe happened. For example, there is a famous study in which psychologists asked subjects to recall meeting Bugs Bunny at Disney World, and many did agree that they remembered meeting Bugs with extreme detail. However, this would be impossible because Bugs is not a Disney character. I also have the false memory of believing I had the stomach flu during elementary school one fall. However, the truth is that I went on a road trip to South Dakota.
Childhood memories have always been difficult to recall, due to childhood amnesia, and there are also memories that we strongly believe occurred that are nothing more than figments of our imaginations. Try to experiment by asking yourself to recall certain memories from your early childhood, especially memories that you are uncertain of, and then checking the accuracy of those memories with parents or other adult individuals who were there. After experimenting with this you may be surprised by which memories are actually based off of past events.