Margo Guryan wrote "Think of Rain" which Harry Nilsson recorded during his Aerial Ballet sessions. The recording remains unreleased.
He promised he would let me hear it, but we learned that although the song was listed on a tape box it was spliced out by Harry. Apparently he did that when he was unhappy with something he had recorded.
-- Margo Guryan (2017) 
We learned from someone at RCA who was compiling a Nilsson package that "Think of Rain" was listed on a tape box, but razor-cut out. (Harry apparently did that when he didn’t like a performance.) Harry told me that he had tried recording the song many different ways - fast, slow, hard, soft - but nothing worked. He said he’d let me hear it, but never did. So it was never released, I never heard it, and the public will never hear it. Alas!
-- Margo Guryan (2012) 
I already had a telephone friendship with Harry Nilsson. He recorded "Think of Rain" but didn't like the way it came out. It was never released. And, though he promised, I never heard it. He gave it to Judy Carne who performed it on "Laugh-In."
-- Margo Guryan (2015) 
Asked in 2018 about her songwriting and arranging process, Guryan mentions Harry:
The "arrangement" was usually part of the song as I was writing it. I didn’t write a song and then attempt to arrange it. That never worked for me, although it worked beautifully for others. George Tipton, who arranged Harry Nilsson’s "Without Her" is a case in point. It was the first song written by Harry that I heard. The cello line that Tipton employed is magnificent! Though I admire the contributions of many brilliant arrangers, my arrangements were always written into my songs.
-- Margo Guryan (2018) 
-  writingonmusic.com, Fiona McQuarrie (2017-03-06) " Heartaches and Raindrops: Margo Guryan’s "Think of Rain"" (https:/
/) writingonmusic. com/ 2017/ 03/ 06/ heartaches- and- raindrops- margo- guryans- think- of- rain/
-  " Margo Guryan :: The AD Interview" Aquarium Drunkard (2012-09-27) (https:/
/) aquariumdrunkard. com/ 2012/ 09/ 27/ margo- guryan- the- ad- interview/
-  Salon.com, Benjamin Wheelock (2015-08-12) "You Must Hear This! Margo Guryan's "Sunday Morning"" (https:/
/) www. salon. com/ 2015/ 08/ 12/ you_must_hear_this_margo_guryans_sunday_morning/
-  It’s Psychedelic Baby, Klemen Breznikar (2018-03-18) "Margo Guryan - Interview" (https:/
/) www. psychedelicbabymag. com/ 2018/ 03/ margo- guryan- interview. html