“What did the baby corn say to its mom?”/“Where’s my pop corn?”

Popcorn is the subject of a frequently told joke:
   
Q: What did the baby corn say to its mom?
A: Where’s pop corn?
 
The joke has been cited in print since at least 1977.
   
“Who called them dad jokes instead of pop corn?” is another “pop corn” joke.
   
       
Google Books
More Ballpoint Bananas
Compiled by Charles Keller
Illustrated by Leonard W. Shortall
Englewood Cliffs, NJ: Prentice-Hall
1977
Pg. 31:
What did the baby corn say to the mother com?
 
24 April 1977, The Robesonian (Lumberton, NC), The Mini Page sec., pg. 3, col. 1:
Q What did the baby corn say to the mother-corn?
A “Where is popcorn?”
Peggy Hunt, age 11, Rowland
 
Google Books
The Purple Turkey and Other Thanksgiving Riddles
By David A. Adler
Illustrated by Marylin Hafner
New York, NY: Holiday House
1986
Pg. ?:
What did one baby ear of corn say to the other?
Where’s pop corn?
 
Google Groups: rec.humor
Laffy Taffy sample jokes
Tom Rombouts
8/10/90
(...)
Q:  What did the baby corn say to the momma corn?
A:  Where’s my pop corn?
 
11 August 1998, Augusta (GA) Chronicle, “Mighty Funny’s Mini Jokes,” Xtreme sec., pg. 15 (?), col. 3:
Q: What did baby corn say to the mama corn?
A: “Where is popcorn?”
(both sent in by Keith Conrad)
 
Twitter
JokesByKids
‏@JokesByKids
From Emily, age 12, United States: What did Baby Corn say to Mommy Corn? http://cli.gs/WJAXR
4:50 PM - 14 Sep 2009
 
The Huffington Post
10 Of The Corniest Food Jokes On The Planet
By Alison Spiegel
Posted: 07/02/2014 9:43 am EDT Updated: 07/02/2014 9:59 am EDT
(...)
Q: What did the baby corn say to its mom?
A: Where’s my pop corn?