What is the value of a US 20 dollar bill with a brown seal?

There are many varieties of US $20 bills that have brown seals, but only two types were printed in the 20th century - the 1929 series of National Currency Notes and the 1934 series of wartime currency printed for use in Hawaii.

Please see the questions

• What is the value of a 1934 US 20 dollar bill with HAWAII on it?
• What is the value of a 1929 US 20 dollar bill?