Does anyone know about antique STAMPS ?

I have several very old Ben Franklin 1 cent stamps attached to some very old famliy letters and post cards. The first is a hand written letter wrote and sent in 1857. It has three blue colored Ben F. 1cent stamps on it. he faces to the left on these. Secondly, I have a green colored Ben F. 1cent post marked 1910. this one has a three leafed pattern that run up the side's of Ben franklins bust. He faces to the left on this one to. The last one is a Ben F. 1cent green colored stamp from 1908. On this one he's flanked on both sides by greek type men holding up the word United States of America. It also has yhe years 1706 - 1790 beside his name at the bottom. I have pics if anyone needs to see them. Are these valuable or rare? please help with any info you may have. Thank you Rob