Why do you think Atwood chose bread as her subject in the story? Why not some other food like pizza or ice cream?

its a very common object her readers can easily understand.

Explanation:

Since 'bread' is often generally used to refer to food (or sustenance), by using 'bread' in her story, Atwood could easily relate in a humorous way how she learned to appreciate whatever possession or food she had.

And she could further encourage others to share their 'bread' with those who are less privileged in their community.