What should I do with a toy that my son found lying on the ground in a shopping mall, knowing that such toys usually come with children's meals?

There is no obligation to return a toy picked up by the son if it was lying on the ground and accessible to every child, as it is considered ostensibly his property. However, if the toy belonged to a specific child who had previously acquired it, it must be returned to him. If that is not possible, its value should be given as charity on his behalf. The owner is then given the choice, if he comes later, between ratifying the charity or receiving a similar item. If the toy is of negligible value, there is no harm in using it.