The 1934 National Parks Issue
(read how to value your stamp below)
You have the National Park issue from the year 1934. The 3¢ value is quite common.
The perforated variety (Scotts #742) value can be found by clicking here.
The imperforated variety (Scotts #758) value can be found by clicking here.
The souvenir sheet's (Scotts #750) value can be found by clicking here. Or Scotts #770 which looks exactly the same but has a wide gutter between each souvenir sheet and its adjacent souvenir sheet. Number 770 can be located by clicking here. The sheet is shown below
#770 showing wide gutter between blocks