The stamps appear to be five $ 1.00 stamps.
[When the Civil War erupted in 1861, the country was on the verge of bankruptcy. A plan was developed to generate internal revenue – money collected from taxes placed on domestic items such as tobacco, alcohol, medicine, perfume and playing cards. Stamps were provided as proof of payment. Examining used U.S. Revenue stamps offers a window into the past – the government required several unusual cancellation techniques such as private cancels, manuscript initials and perforated initials.
The same legislation that created these stamps also created the Internal Revenue Service (IRS) and the Bureau of Engraving and Printing (BEP).] Mystic Stamp Company has this posted on their site