Another foreign favourite of mine is Amarcord by Fellini. Ok, so it's Italian, not French, but well worth watching.
It's all about a little Italian town set in the 30's and one of the best scenes is set in a kid's classroom. Bloody hilarious, so do check it out.
Can't believe that no-one's mentioned the films by Claude Chabrol. Probably one of the greatest French film directors ever!
He was called the Alfred Hitchcock of France and my favourite is a bit old but still brilliant, called Le Boucher (The Butcher).