What are the best toys to give to a baby less than 6 months?

My little one's first toy is her play gym with hanging toys. It helps her reach for something so as to exercise her arms. Whenever she touches one of the hanging toys, it would move, she could feel the grasp in her hands and hear the sound that it makes. In that sense, she would repeatedly do those things that would awaken her senses. Another thing is our curtain. We have this colorful curtain that whenever the wind blows, would move on top of her that she would scream out loud!!! It makes me smile that no other toys could give her that same effect, so yes, I consider it as her toy..