Please keep in mind that I am simple country girl who was really not introduced to 'real art' until I took the required art history course in college. From what I didn't sleep through (it was a dark auditorium with cushy stadium like seating once a week in the afternoons....and the prof spoke softly and rather monotone...you would have too...don't judge me....) I learned a lot. Here are my all time favorites no matter how cliche - they really do speak to me.
Starry night - Van Gogh

I hope to have this print hanging in a navy blue/white/pale yellow themed master bedroom some day.
Dali - The Persistence of Memory

Eerily fascinating to me.
Edvard Munch _ The Scream

This is how I feel most days. I can relate.
The works of Edward Weston

I loved all his work. So simple yet liberating - almost like you are looking at something naughty.
These are the ones I recall off the top of my head so they must have made and impact b/c I knew what names to Google for the images.
Hope you like them as much as I do!