It's part of a Precision Farming exhibit, as Lee is describing the first time he rode in a combine with a yield monitor:
Here's how Lee described it:
"We were in the combine cab and all of a sudden this machine registers 135 bushels, then shoots up to 150 and then to 179….when we came to a wet spot it would drop down to 35 bushels and then shoot back up to 160….Astounding…"
The display includes a picture of Lee, which he says he's never seen!
Listen to how this all came about and Lee's reaction here: