I can somewhat relate to what you wrote at the beginning about talking to your mom on the phone.
I find I like talking to my mom best when the subject of art comes in. So whenever she gets into the loop of talking about things that interets only her, I try to bring the conversation back to what interests both of us - how she teaches drawing at school, what I draw or what I play.
Otherwise, it's better to just keep silent...
Yeah, it's funny how we learn what the "safe subjects" are with certain family members.