The FAA info I dug up with a quick search mentioned 500ft and up is considered "free airspace". Under that is land owner's and the planes cannot interfere with the enjoyment and use of the land.
No idea if the guy circling for 3+ hours was under 500ft or not. Was low enough that I could easily see him in the cab. Was loud enough I probably needed earplugs to be under 85 dB.
Reason I was asking is I was thinking about putting my drone in the air to get photos of my land to help with site planning. IE where I'm putting a 30x48 steel building I have, a house, rentals, etc. BUT I was concerned about all the planes flying over my house.
In theory, as long as I'm not above 500ft, I should be fine?