Richard C (Craven / Canard) - Original Mail Art "Poem by Richard C" envelope with collage (Signed)

Richard C (Craven / Canard).  Poem by Richard C. Thomasville: Self Published, 1973 (?). Envelope with collage.   4 3/16" x 9 1/16". Very good.  Envelope with one torn side and neat masking tape on the other. Light soiling and edge wear.  Postal markings, a stamp and hand-written addresses.  Original Mail Art Envelope and collage made by Richard C and mailed to fellow mail (and Fluxus) artist Ken Friedman.  Envelope has "Poem by Richard C" rubber-stamped on verso above a pasted picture of Mick and Bianca Jagger with pasted text about Mr. & Mrs. Lennon.  Enclosed is a twice-folded piece of paper with a picture of Yoko Ono and John Lennon on one side.  "Poem by Richard C" is rubber-stamped between them and  towards bottom is a pasted caption  "Rolling Stone Mick Jagger and wife, Bianca." A joke about the interchangeability of then contemporary rock stars?