Toys are things like dolls, stuffed animals, legos, blocks, etc. I don't know what a "duck-like life-buoy" is but it's a toy if you played with it when you were a child. This sounds similar to something we would call a "rubber duckie". Anything can be a toy. Parents usually decide what is a toy and what is not. If they don't allow their children to play with something, then it is not a toy and they will say so. "Don't play with that. It's not a toy". A "mouth organ" (or harmonica) can a toy if it is meant to be used by children, like one of those cheap plastic ones. A high-quality harmonica that a professional musician would use is not a toy.