"farm fresh"
I do not believe adding this label requires you to legally meet any specific requirements
Whereas "cage free" "organic" "free range" I believe all have certain requirements to be met to be used on your label... but if your situation meets any of those requirements, those are labels people like to see!
Depends on state, so make sure to do your research. I believe in some states you can't even mark it as "farm fresh" if you're a backyard seller. You may need a license to sell eggs at all.
I don't sell my eggs, most of them end up going to family members who want them. I have a hard time eating so many eggs myself.