Stories about your hobbies are always a safe bet. If you like reading, you can share about a really good book you've read recently. I love reading mystery novels, and I often tell my mom about the plot twists and interesting characters in the books I've just finished.
You could share stories about your achievements at school, like getting an A on a difficult exam or winning a school competition. For example, I once got the highest score in a science project, and my mom was so proud when I told her all about the research and hard work that went into it.
Travel stories are also great. If you've been on a trip, you can talk about the interesting places you visited, the local culture, and the people you met. I went to a small village during a vacation and told my mom about the unique handicrafts I saw there and the friendly villagers who showed me around.