What does the idiom a farmer eat what he know mean?

The idiom "a farmer eats what he knows" is not a common or standard idiom. It likely comes from a misunderstanding or misremembering of a similar idiom.

It's possible the person meant to say "a farmer eats what he grows," which is a much more common and recognizable idiom.

Here's what it means:

* "A farmer eats what he grows" signifies that people often consume what they produce or what they are familiar with. It suggests that our choices are often influenced by our experiences, skills, and resources.

Let me know if you'd like to know more about common idioms!