The Rev. Al Sharpton said yesterday at a church in Los Angeles that he is requesting that the U.S. Postal Service issue a Michael Jackson commemorative stamp, E! Online reports. The USPS typically requires a five-year waiting period after a death before issuing stamps. Sharpton also called for a national day of mourning, urging people to gather in schools, community centers, and churches to pay tribute to the singer on Tuesday, when a public memorial service will be held at L.A.’s Staples Center.