What should we do when we see food thrown on the ground outside the house?

It is not permissible to discard food that is fit for consumption when it is possible to benefit from it, because that is a waste of money, which is forbidden by Islamic law. Whoever sees discarded food that is still good, will be rewarded if they are able to salvage it by giving it to the poor or preserving it for future need. However, if they are unable to do so, or if the food is not fit for consumption, then there is no blame on them.