How to Get the Mayor's Key in "Final Fantasy IX"by Shea Laverty ; Updated September 22, 2017
Home to the dark factory that spawned the Black Mages, Dali is a small rural town in "Final Fantasy IX." Although the town harbors few secrets quite as terrible as the factory, there is a secret area next to the windmill accessible only with the Mayor's Key. The area only has a couple of items, but one of them is absolutely necessary to complete the coffee quest from Morrid on Observatory Mountain -- and quite easy to miss.
Obtaining the Key
For most of the game, the Mayor's Key is unobtainable. You'll be turned away or unable to enter the building until you enter the card competition in Treno during Disc 3. This is the only time you can get the key, so head to Dali and enter through the south gate. Head to the mayor's house, and search his desk until the child in the house says "Zzz." At that point, check the heater to find the Mayor's Key. The key is unobtainable after completing the card competition, so this is the only chance you have to get it.
Exploring the Locked Area
Enter the windmill and go to the door in the upper right area. This door is locked for most of the game, but now that you have the Mayor's key you can exit through it. The door leads to a small walled-in courtyard, with a single chest on the right-hand side. Opening the chest will net you 30,000 Gil -- but more importantly, checking it again afterward will turn up the Burman Coffee. This coffee is an item for Morrid's coffee quest, which earns you the miniature Prima Vista item when completed; this will permanently raise your Treasure Hunter rank.