Just wanted to add that silk is a type of material, while satin is a type of weave, and you can have silk satin (which won't be vegan, in that case).
You can use silk/satin (or any other smooth material) scarves to both cover the pillow and/or wrap your hair/head with.
I bet if your mom tried it, she would notice a difference, too.
By the way, silk/satin pillowcase is a good preventative for wrinkles, too, as it doesn't absorb oils/water as fast and your skin glides over it. I don't see how it's vain: you have to sleep on something anyway, so how is it vain if it's on smooth material instead of a more absorbent one?