“What do you get if you cross a sweet potato and a jazz musician?”/“A yam session!”

A yam riddle is:
 
Q: “What do you get if you cross a sweet potato and a jazz musician?
A: A yam session>
 
The joke has been cited in print since at least 1996.
 
   
24 December 1996, Chicago (IL) Tribune, “Playing Around,” sec. 7, pg. 9, right masthead:
Q. What do you get if you cross a sweet potato and a jazz musician?
A yam session.
 
Google Books
Uncle John’s Book of Fun
By Bathroom Readers’ Institute.
New York, NY: Portable
2004
Pg. 143:
Q: What would you get if you crossed a sweet potato with a jazz band?
A: A yam session.
 
Twitter
YoKid‏
@YoKidorg
#wackywednesday Q: What would you get if you crossed a sweet potato with a jazz musician? A: a yam session. Sweet 😊
8:25 AM - 9 May 2012
 
Twitter
Garden City Jazz‏
@GardenCityJazz
What do you get if you cross a sweet potato and a jazz musician?
(A yam session!)
#Jazz4Kids July 17 Diamond… http://fb.me/249jsSf68
7:27 AM - 15 Jul 2012
 
Twitter
Robby Aces ⚒‏
@RobbyAces
My boy got old school jazz jokes.
Q: What do you get when you cross Thonious Monk with a sweet potato?
A: Yam session
3:00 PM - 2 Feb 2013
 
Google Books
Food Jokes For Kids 3
By Peter Crumpton
PeteyRF Creative
2015
Pg. ?:
What do you get if you cross a sweet potato and a jazz musician?
A yam session!