There is nothing to indicate that Calvin Coolidge had any particular animosity towards farmers, but he did do one thing during his administration that farmers particularly did not like. This was the fact that Coolidge twice vetoed the McNary-Haugen Bill.
McNary-Haugen was a bill that was meant to keep farm prices high. It was supposed to do this by having the government buy up farm surpluses at guaranteed prices. The government would then sell what it had bought to other countries. By doing so, the government would be helping farmers. Farmers twice pushed Congress to pass this bill but Coolidged vetoed it twice.
Coolidge did this because he did not believe that the government should be spending its money to prop up farmers' income. This was not motivated by dislike of farmers but rather by a dislike of big government. He believed, as many conservatives do today, in free market solutions to all problems.