The rate for a United States postage stamp (or a one-ounce letter) was 22 cents in 1987. The rate for the first ounce of a package was the same.
The stamp used for USPS letters in 1987 was called the "D stamp." This stamp was used from February 17, 1985 to April 3, 1988, when the new "E stamp" (with a postage increase to 25 cents) was introduced. During this period, additional package ounces cost 17 cents per ounce to ship, and the postcard rate was 14 cents. Most of these D stamps were green in color, as the USPS had printed 6 billion of them in 1985 prior to the rate increase.