The ending is so cute and unexpected! Maybe some words could be simplified a little? Ie. Supermarket could be shop? Maybe medicine is a bit complex? I would love to hear Grandma's poem about Liberty bell-that part was very intriguing and specific. Maybe a few lines of the poem could be revealed, and reoccur through the story?
I love how you invoked multiple senses with your writing, ie smell, taste, sound. I feel like I'm in the environment when I'm reading about it. This is a very small thing, but I was wondering if oysters might be too complex a word/food for small children? They sound really delicious though.