One side of me, the nurse side would have ask for a glove, scooped it up, and tossed it in a waste container.
The other side of me the mom of adult children, would have said, "Nope this is a hospital and watched my child." (and I'm not saying you didn't watch your child) I know some are gonna scoff :chair: but I'm from the school of parenting where accountability is my responsibility. Home or away, small children need to be watched. After all, this didn't occur at a daycare center.
It is impossible to say what kind of a "patch" this was, if it had any medication or if it was left by a healthcare worker or a patient. Lesson learned; You're observant, conscientious, and concerned all of these are fine qualities which will enhance your nursing career.