Avignon is a city in the South of France.
guakasite, wikitalk just walked to Route de Lyon, found a nice traffic light, hitched a ride in 5 minutes, was dropped at the Peage of the highway and hitched another ride there in 5 minutes. Jason has hitched out of Avignon twice and did it without problem. Perhaps it may be best to fly a sign for the motorway to Paris (A7?) and get to the peage. From there, you'll find many people going every direction. To begin hitching, head out out the city walls and follow the signs.
Beyond the city walls and by the river, there are many fields in abundance and possible sheds to fend off the rain.
Search around and you can find fantastic skips full of bread and vegetables/fruit. Get away from the tourist area a little if you can to find more success.