Well, I always felt this way around my family- I am the first to leave the midwestern farm life and go to college, so I have always felt a bit disconnected from them on some level (being gay, being educated, urban life, etc) and embarrassed about my background. But I can't think of a specific time this happened.
I think my dream is related to letting go (purging the stones) of feeling this way about my past, and not letting myself feel intimidated or 'less than' someone else because of it.
And it is significant that I did feel as those I easily 'passed' her exam!