“What did the farmer give his wife for Valentine’s Day?”/“Hogs and kisses.”

A Valentine’s Day riddle is:
 
Q: What did the farmer give his wife for Valentine’s Day?
A: Hogs and kisses.
 
The joke has been cited in print since at least 1998.
 
   
14 February 1998, The San Bernardino County Sun (San Bernardino, CA), “Funny Bones,” pg. D8, col. 1:
Here’s a joke sent by kids to the Rosie O’Donnell Show.
QUESTION: What does a farmer give his wife on Valentine’s Day?
ANSWER: Hogs and kisses.
 
Google Books
Super Goofy Jokes
By Jacqueline Horsfall
Illustrated by Rob Collinet
New York, NY: Sterling Publishing Company, Inc.
2005
Pg. 86:
What do farmers give their wives when they marry?
Hogs and kisses.
 
Google Groups: alt.humor.puns
Kids Puns of the Weak 0-15-05
Stan Kegel
2/15/05
(...)
What do farmers give their wives on Valentine’s Day?
Hogs and kisses!
   
8 February 2009, The Sunday Mail (Brisbane, Queensland), “Jokes,” pg. F6:
What do pig farmers give their wives on Valentine’s Day?
Hogs and kisses!
 
Twitter
Andrew
‏@StuntmanPsyK
@Scottymagic What did Farmer John give to Farmer Jane?      Hogs and Kisses
5:04 PM - 30 Apr 2009
 
Google Books
A Man Walks Into a Bar 3
By Jonathan Swan
New York, NY: Random House
2010
Pg. 112:
What do farmers give their wives on Valentine’s Day? Hogs and kisses!
 
Twitter
Charlie
‏@charliesjokes
What did Farmer Joe give Farmer Jill for her birthday? Hogs and kisses! #joke
8:18 PM - 4 Feb 2010
 
Twitter
MoRoCo Chocolat
‏@morocochocolat
What did the farmer give his wife for Valentines Day?.. Hogs and kisses.
1:33 PM - 13 Feb 2010
 
12 February 2012, Los Angeles (CA) Times, “The Kids’ Reading Room; Jokes & Riddles,” pg. H4, col. 3:
What do farmers give their wives for Valentine’s Day? Hogs and kisses!
Carina, 12
Oxford Academy, Cypress
 
Google Books
Funny Valentine’s Day Jokes to Tickle Your Funny Bone
By Linda Bozzo
Berkeley Heights, NJ: Enslow Publishers, Inc.
2013
Pg. 6:
What did the farmer give his wife for Valentine’s Day?
Hogs and kisses.
 
Google Books
Valentines Day Jokes
By Peter Crumpton
PeteyRF Creative
2015
Pg. ?:
What do farmers give their wives on Valentine’s Day?
Hogs and kisses!