It very much depends what you mean by 'Biblical story proven to be true'. Some of the characters in the Bible were known to have definitely existed (e.g. Pontius Pilate). The siege of Jerusalem happened.
If you mean the miracles in the Bible - then no, nothing comes to mind.
But perhaps the most surprising is the Deir Alla inscription. Balaam is a relatively minor character - a diviner mentioned in the Book of Numbers. There was nothing to suggest that this character existed other than the Bible.
In 1967, at Deir Alla, Jordan, archaeologists found an inscription carbon dated to 840–760 BCE mentioning this person. Although there are noticeable differences (e.g. he is a prophet of Ashtar and not Yahweh) and it only mentions that he existed, it's pretty amazing that the name matches up - consider that the oldest surviving copy of the Bible dates to the 2nd century BCE (so it'd be like us talking about people in the 1400's - but without the benefit of a printing press to keep proper records).
P. Kyle McCarter Jr., The Balaam Texts from Deir 'Alla: The First Combination",Bulletin of the Schools of Oriental Research 237
Allan Millard (2006). "Authors, Books and Readers in the Ancient World".