I would just collect as much as I can, keep part of it, donate part of it ( it'll make me feel good). But one should just check whether it's a trick played on unsuspecting people, while some TV anchor is filming this for the fun section and laughing at your or my expense.
In addition, I will take a note of the environment all along & throughout waiting for the another opportunity & will go for more efforts to collect more money than what I has collected the last time. Taking a precaution, I would start carrying a jumbo bag with me which will also get flexible when required. But I do feel that it's time for me to wakeup from this dream & begin looking for interviews if any.
I remember a story by Leo Tolstoy - How much land does a man require? I read it long back but it is still fresh in my mind.
A person was given freedom to have as much land as possible by running around it and covering it in a closed shape by reaching the starting point before sunset. He could not reach back to the starting point and instead in his greed lost his life on the way.
So the question how much one will be able to collect in that situation seems to be a fearful proposition. A good citizen will simply report it to the authorities and return to his house for a refreshing cup of tea.
Knowledge is power.