Here is a puzzle I made up that barred access to a door the party had to go through (I made it about 15 years ago). Hanging on the wall beside the door was this set of picture tiles. Each tile could be pushed. If the incorrect tile was pushed the pusher took damage and if the right tile was pushed it lit up. The right sequence would open the door. There was no explanation along with the set of tiles; the players had to figure out what the puzzle was looking for, which made it a bit more difficult.
Instead of simply allowing the players to roll some dice to solve the puzzle I made the players actually figure it out themselves. However, if you were to utilize this puzzle yourself then you can allow your players to solve it in any way you deem. I also recommend printing out some extra copies for multiple players to look at. Its annoying for everyone to be looking at one sheet and eventually some players will simply stop trying, which is not the goal here. You can rationalize it by saying the characters quickly draw copies.
Below is a hint that you can give the players if they seem to be stuck and they make an appropriate roll on a releveant skill (History, Intelligence, etc). I'm moving the hints further down in case you want to try and solve the puzzle yourself first. Behind the break will be the answer.
Hint #1: With so many unique symbols, perhaps you need to find two of the same.
Answer: You are looking for the two symbols that look the same. If I did it right there will only be one set, however, if your players find a different set that is fine as well. The set I made sure was in the diagram can be found at...
(From the top left corner)
4th column and 7th row
6th column and 11th row