The few French folksogs I know are pretty standard:

Chevaliers de la Table Ronde
Perrine Etais Servante
Aupres de ma Blonde
A La Claire Fontaine
Les Bouchees A La Reine (really dirty)
plus a few more modern numbers like Georges Brassens and a couple of Francois Hardy's tune which don't qualify as folk, I guess:

Le Petit Cheval Blanc
Monsieur le President
Ton Meilleur Ami
Je Veux Qu'el'qu'un Qui M'Aime

Maybe one or two others tucked in the dustier back corners of memory.

Amos