(read how to identify your stamp below)
You have the 30¢ Buffalo from the years 1923-30. It is a somewhat common stamp and is worth no more than a dollar or two if used.
To determine the difference the two varieties of the 30¢ Buffalo one needs to look at the perforations. You will need a copy of the very common 1932 3¢ Washington (#720). A picture of which is shown below. Follow the instructions below
There is another way of determining the difference between #569 and #700, that is to look at the type of printing. #700 was printed using the Rotary Press Printing which makes the stamp wider and longer than #569 which was printed using the Flat Plate Printing method. An illustration of the degree of difference between the two printings is shown below;
Lastly #569 tends towards olive brown whilst #700 tends towards brown.