In Hebrews 9:14 we are told that the ark contained the stone tablets of the law, a golden jar of manna, and Aaron's staff that had budded.
However in 1 Kings 8:9, when Solomon brought the Ark into the Temple which he had built, it only contained the stone tablets. The other contents, the rod and the jar of manna, must have been removed at some point before the ark was brought into the temple. And that is all the Bible says about the contents of the ark of the covenant.