"Dig the Potato Garden" joke

An old man lived alone in Idaho. He wanted to spade his potato garden, but it was very hard work. His only son, Bubba, who used to help him, was in prison. The old man wrote a letter to his son and described his
predicament.
Dear Bubba,
I am feeling pretty bad because it looks like I won't be able to plant my potato garden this year. I'm just getting too old to be digging up a garden plot. If you were here, all my troubles would be over. I know you would dig the lot for me.
Love Dad
A few days later he received a letter from his son.
Dear Dad,
For heaven's sake, dad, don't dig up that garden, that's where I buried the BODIES!
Love Bubba
At 4 the next morning, F.B.I. agents and local police
showed up and dug up the entire area without finding any bodies. They apologized to the old man and left. That same day the old man received another letter from his son.
Dear Dad,
Go ahead and plant the potatoes now. That's the best I could do under the circumstances.
Love Bubba.