Even the members of the Brotherhood of Steel need to eat. You can begin this Radiant quest after completing Tour of Duty and by talking to Proctor Teagan.
He will ask you to visit a randomly designated farm and to convince the locals to give some of their crops to the Brotherhood. In our case, we ended up at the Warwick Homestead.
There are various methods of persuasion with these settlers, whether by threat, bribe, or charm. The choices become clear in the conversation options. When you've secured the goods, return to Teagan for your reward. This quest is repeatable.