It was during the 1960s that Warhol began to make paintings of iconic American objects such as dollar bills , mushroom cloud s , electric chair s , Campbell 's Soup Cans , Coca-Cola bottles , celebrities such as Marilyn Monroe , Elvis Presley , Marlon Brando , Troy Donahue , Muhammad Ali , and Elizabeth Taylor , as well as newspaper headlines or photographs of police dogs attacking African-American protesters during the Birmingham campaign in the civil rights movement .