For a complete list of all the US Post Offices, the amount of each stamp issued, where it
was mailed from and almost everything else you would want to know refer to the link

For example, using the search box below, type in the word registered mail,
the first search gives you the index page, press next on the search box
and you will see a page which tells you how much registered mail cost. Then
it goes on to pages that explain how registered mail works, how it is sent and
even more interesting, how it is sent to foreign destinations (Cochin China
went by Tacoma or San Francisco). Have fun.