Auxiliary handstamp, PAID
Although the markings on this early American handstamp are illegible, it is like that it is a "PAID" marking. \The most common usage of "PAID" markings was prior to the introduction of adhesive postage stamps in 1847. This marking on a mailpiece indicated that postage was prepaid by the sender.
Wooden handstamps were a low-price alternative to metal stamps in an era when postmasters at small offices were required to procure supplies at their own expense. A tight-grained wood was hand-chiseled to leave intaglio lettering on the marking face. After heavy use which wore the lettering, a postal clerk might attempt to recut the lettering.