what do you do with old stamps?

Posted by Yu Photography (Pleasanton, United States) on 17 October 2006 in Miscellaneous.

have a bunch of old stamps that you never used? my oldest is of the 32 cent variety. well, today, i decided to clean them out and use them (with the help of some h-rate & 2 cent stamps). anyone know the max number of stamps you can put on an envelope?