How can i send a lot of postcards to the USA cheaply from France?

so basically I have been collecting up postcards for my friends in the US for the past month or so since I have been going to school here in France. What I wanted to do was send all of the postcards I have so far addressed to my mother in the US to send out to the rest of my friends. Does that make sense and/or is that even possible? If so is it cheaper that way?