The pygame documentation for mouse events is here. You can either use the pygame.mouse.get_pressed
method in collaboration with the pygame.mouse.get_pos
(if needed). But please use the mouse click event via a main event loop. The reason why the event loop is better is due to "short clicks". You may not notice these on normal machines, but computers that use tap-clicks on trackpads have excessively small click periods. Using the mouse events will prevent this.
EDIT:
To perform pixel perfect collisions use pygame.sprite.collide_rect()
found on their docs for sprites.