And you shall place the ark cover on the ark from above, and into the ark you shall place the testimony, which I will give you.
This seems to be reaffirmed in Melachim I 8:9:
There was nothing in the ark save the two tablets of stone which Moses put there at Horeb, when the Lord made (a covenant) with the children of Israel, when they came out of the land of Egypt.
But the Christian scriptures say that at some point there was more. Hebrews 9:4 says:
This ark contained the gold jar of manna, Aaron's staff that had budded, and the stone tablets of the covenant.
Since Hebrews was probably written by a Jew, and was definitely written to Jews, it would seem strange to me if this notion was different from Jewish thinking of the time of writing.
So do any Orthodox Jewish sources say either that there was only the testimony, or that there were other items?