To my knowledge my mother never knew, only my oldest sister, and that came about accidentally. We had decided as kids to go trick-or-treating as each other. We went in the bedroom, undressed, I grabbed her panties off the bed, put them on and got the biggest erection of my young life. She stood and stared, started to laugh, wanted to touch it. It was an awesome feeling. She let me take her panties from time to time to watch it happen again. It was our secret til her death....but her gifts kept on giving.