The quick answer is "No." However, there has been a lot of speculation on this.
We do know that the accusers of the woman left without stoning her after Jesus said, "He who is without sin among you, let him cast the first stone at her," but apparently none of them left before He did this. We also know that the older ones were the first to leave.
So, what He wrote on the ground could have been irrelevant, and the people left perhaps under conviction from the statement alone.
One interesting suggestion is that Jesus was writing out the 10 Commandments. If so, it could have been that the accusers realized that they were guilty of breaking the law. "Honor your father and mother" comes before the "Thou shalt not commit adultery". Also included are the prohibition against bearing false witness and coveting, both of which could likely have indicted all of the accusers.
It is also possible that Jesus was writing other specific commandments (outside the ten commandments) of which each person was guilty of breaking.
Yet, again, we don't really know. We aren't told, so we can conclude that it wasn't important for us to know. What Jesus wrote may or may not have added to what drove the accusers away.