“Migraine” sounds like “my grain.” “I don’t get headaches, but America’s heartland gives me my grains” was posted on Twitter on August 5, 2011. “Caffeine gives me headaches, but bread gives me my grains” was posted on Twitter on August 24, 2015.
   
A farmer is often inserted in the joke. “What kind of headaches do greedy farmers get? MY GRAINS!” was posted on Twitter on August 14, 2012. “What kind of headaches do wheat farmers get??? My grains” was posted on Twitter on February 5, 2013.
 
     
Wikipedia: Migraine
A migraine is a primary headache disorder characterized by recurrent headaches that are moderate to severe. Typically, the headaches affect one half of the head, are pulsating in nature, and last from two to 72 hours.  Associated symptoms may include nausea, vomiting, and sensitivity to light, sound, or smell. The pain is generally made worse by physical activity. Up to one-third of people have an aura: typically a short period of visual disturbance which signals that the headache will soon occur. Occasionally, an aura can occur with little or no headache following it.
   
Twitter
Alec Sulkin‏
@thesulk
I don’t get headaches, but America’s heartland gives me my grains.
4:08 PM - 5 Aug 2011
   
Twitter
Alan Machnik‏
@Alan_Machnik
Doctor says it’s not my neighbour’s wheat or his maize that’s giving me headaches. He said it must be my grains.
3:40 AM - 16 Feb 2012
 
Twitter
Brandon Lopez‏
@bollopez
What kind of headaches do greedy farmers get? MY GRAINS!
4:11 PM - 14 Aug 2012
     
Twitter
TalentlessMedia‏
@TalentlessCook
I’m going to come up with a cereal just for women with headaches and call it My Grains.
3:25 PM - 14 Sep 2012
   
Twitter
Jon Zondervan‏
@jonzondervan
What kind of headaches do wheat farmers get??? My grains.  #TerribleJokeTuesday #fb
1:28 PM - 5 Feb 2013
   
Twitter
Your Favorite Joel‏
@urfavoritejoel
What does wheat call its headaches? My GRAINS lol I’m funny pls tell your friends
12:03 PM - 15 Mar 2013
   
Twitter
Nonsensei Yusri‏
@NeoVersion7
Being a Farmer gives me Headaches… I have nothing but my Grains! http://youtu.be/6YMPAH67f4o
8:40 AM - 5 Sep 2013
   
Twitter
random ramblr‏
@RandomRamblr
If I was a farmer, I’d probably get headaches from my grains.
2:21 PM - 16 Apr 2014
         
Reddit—Dad Jokes
What did the farmer say when a headache prevented him from harvesting his barley? (self.dadjokes)
submitted April 13, 2015 by karlrocks23
My grain.
   
Twitter
Bread Savage‏
@papasuncle
Caffeine gives me headaches, but bread gives me my grains.
6:15 PM - 24 Aug 2015
 
Reddit—Dad Jokes
Why did the farmer get arrested for having headaches? (self.dadjokes)
submitted February 15, 2017 by IONTOP
Because he had my grains
 
Twitter
Dad Jokes‏
@dadsjokes
What kind of headaches do selfish wheat farmers get? My grains!
(Thanks Bruce)
9:15 PM - 16 Nov 2017
 
Reddit—Jokes
What kind of headaches do wheat farmers get ?
submitted January 11, 2018 by MJAMPLIFY
My grains.