What's mine is hers and what's hers is hers

Remember that old saying "Whats mine is her and what's hers is her" in relation to marriage? It also applies to mother-child relationships. I had this really cool floor lamp in my room that someone gave me, with five flexible head and multicolored shades. I was using it as a reading light. All of a sudden, my mom decides that it would work really great in her sewing room to light up her sewing machine. Since I'm still under her roof, I have no choice but to give it to her. Now I will probably never get to use it again, as she will forget it's really mine. I then ask if I can replace said lamp with another floor lamp in the house that is sitting in the corner of the dining room unused. And what does she say? "No, we're moving in 6 weeks and we should be putting things away."