“Daily Themes” is a classic Yale course, where students write a 500-word essay every weekday for an entire semester.
When I took the class in 2015, I saved all the themes in a spreadsheet:
If you need writing prompts, I recommend these!
As a bonus, here’s a great Calvin Trillin story on the history of the class (requires New Yorker subscription or a way to sneak around the paywall).