sheets we keep on the floor of our bedroom closet (which ordinarily stays closed).
After witnessing Cleo acting as though these things were treated with catnip I decided to research what was actually in them. Now I feel horrible for not looking into this sooner, though she was only able to get to them when we opened the door, and only if she was interested (something she can turn on and off like a light switch).
Had I done my homework and realized the potential harm these sheets can cause we never would've let Cleo play with them.
After reading about the dangers of pets playing with these, and in some cases actually eating them, we no longer leave them on the floor.