Exodus 16:34 in some bible versions mentions some tablets and I was just wondering if anyone knew what was on those tablets.
Apparently the verse you are referring to is a little bit anachronistic and it may actually be referring to the tablets you probably know as the ones that have the ten commandments, although at this point in the story Moses hadn't gone up yet to the mount to receive them from god. Read the Matthew Poole's Commentary
This text only tells us that Aaron did lay it up, but it doth not determine the time, nor affirm that it was done at this instant
The tablets, according to the bible, contained the Ten Commandments plus other laws or words as the following verses state,
Exodus 31:18, Exodus 34:1, Exodus 34:27-28
although the interpretations of exactly what was contained are ambiguous. For example read Adam Clarke Commentary
Either a transcript of the whole law now delivered, or the words included from Exodus 34:11; to Exodus 34:26.