David Frye has passed away at the age of 77.  He did a variety of impressions, and the New York Times obituary explains his most famous:

It was Nixon, however, who kept Mr. Frye a regular on the top television variety shows and at the big Las Vegas casinos, perhaps because he was one of the few politicians with a truly Shakespearean richness of character. In one skit Mr. Frye even had the president smoking marijuana and reporting, in hushed tones, “I see spacious skies and fruited plains and amber waves of grain.”