What is in this image? Describe it in Simple English. As plain and simple as possible. No complex words, no long sentences. Still make sure to describe everything in the image.

This is a picture of a mail box with a bird on top. There is a letter in the mail box. A mouse wearing a shirt is next to the mail box. The mouse is holding a heart-shaped envelope. Near the mouse, there is a flower. The image is black and white, drawn in a simple style.