I had a chance to revisited object oriented design patterns recently.   I found a couple online tutorials and watched through them.  I highly recommend the Tuts video: https://code.tutsplus.com/courses/php-design-patterns and the Source Making website.

It’s amazing how every single time I revisit design patterns, I discover something new.  You can visit my notes for this session of design patterns on my Github page where I go into super detail on each of the popular design patterns from both tutorials above.  I hope you find it useful!