Am I allowed to cut flower or branches from public areas like parks? Or even overgrown areas around my house that either belong to the public or the government?
If they are overgrown or for some other reason no one cares you can cut in a way that doesn’t damage anything- But it is a middas chassidus not to:
Have a good Yom Tov
Shulchan Aruch CH:M 359- 1.