Mail Delivery

In the middle of Dinners, you can find the mail delivery building with Artichoke behind the counter. Upon talking to him he gives you a letter for you to deliver. When you deliver all the letters you've been given, talk to Artichoke again to receive your reward (normally more letters).

First letter:

The first letter is addressed to "two screens to the right of Dinners bus stop", which is one screen to the right of the mail building. There you will find Pepper worried about her child. Upon delivering the letter to her, she sees that her child was found and is on the Lost Kid Daycare and moves to Luncheon to help Beans with the lost kids.

First batch of letters:

The middle of 3 square houses in a row:

The recipient is Granita, in Potluck. The letter is a late birthday card sent by Turnip.

2 screens north of the Sips River bridge:

The recipient is Basil, in Luncheon. The letter is from Gelato calling him over to his house in Brekkie. For delivering this letter, Basil gives you a flower named chicory.

To: Beans in Luncheon, From: A Concerned Parent:

The recipient is Beans, in Luncheon. The letter is from an unknown character. After delivering the letter, Beans proceeds to tell you how much of a help Pepper has been with the lost kids and thanks you for delivering the first letter.

The Highest house in Brekkie:

The recipient is Taiyaki in, you guessed it, Brekkie. He's in the top-left screen of Brekkie (same screen as Cantaloupe), in the leftmost house. The letter is a challenge for a duel in the video-game "Mega Mash Sisters". Aw reward for delivering this letter, Taiyaki give you the item Gaming TV.