What is the name of this post-apocalyptic story about a woman reminiscing?

I read it in grade school- it was one of a number of short stories in my McDougal-Littell literature textbook. I recall other stories in that textbook included "All Summer in a Day" and "Flowers for Algernon."

In the story, a woman reminisces about her childhood, during which she spent some time at the sea shore. She thinks fondly about the waves and digging for shells in the sand.
She has a conch shell from this outing, which she has kept for many years, and she likes to listen to the sound of the waves from the conch.

She has not been able to go back to the sea shore because the acid rains and toxic atmosphere have killed all life that is not in a controlled, sealed environment- she herself needs to wear a space suit to venture outside. The reason might have been related to climate change?

In the end, she nostalgically decides to return the conch to the sand by the sea.

What’s the name of this story?
I’ve searched for keywords and for a table of contents from McDougall, but I haven’t been able to find it again.