1900 stamp of Ben Franklin a gem 13 perf

Postcard mailed in 1908 from california. 13 perf sides by 10 perf top and bottom. Riding left side, rare. Stamp centered very good, stamp had uneven perforation tear, that’s rare and distinctive! Lastly the card has been stamped over and over again with pink cancel! How!?!?Have many rare stamps ask for sales.