The 1934 National Parks Issue
(read how to value your stamp below)
You have the National Park issue from the year 1934. The 8¢ value is somewhat common.
The perforated variety (Scotts #747) value can be found by clicking the numbers 766-751 on the menu to the left.
The imperforated variety (Scotts #763) value can be found by clicking the numbers 752-765 on the menu to the left.