What is a plum that has been dried called?

Which playwright wrote the line "We are all born mad. Some remain so"? A plaza in San Francisco is named for which politician, a city supervisor when he was slain in 1978? What word names the plectrum of a harpsichord and a porcupine's spine? A plow appears on the seal of which Cabinet department created in 1862? A plumber uses which long, flexible tool, named for an animal, to clear your pipes? A plump, bearded Dutchman who drove him by sleigh on December 24, 1822, reputedly inspired which man's famous poem? A plunger is also known as which workman's "helper"? What does a pluviometer measure?