My simple question is how can I use pygame.MOUSEBUTTONDOWN on a sprite or item to trigger an event?
e.g. I have item_A and want music to start when I press the object with my mouse.
You will need to poll for events in your main loop, and when you detect a MOUSEBUTTONDOWN event you will need to check if it's on the sprite you want, and if it is then start the music.
How to use pygame.MOUSEBUTTONDOWN?