The 1932 Washington Issue
(read how to value your stamp below)
You have one of the Washington issue from the year 1932. This stamp is very common. Its value can be found by clicking the the number under the stamp that corresponds in appearance to yours.
The left stamp (#720) has perforations all the way around, the middle stamp (#721) has perforations on the sides and the last stamp (#722) has perforations at the top and bottom only