It is illegal to remove anything from parks and reserves. Having said that, it would not be a problem if you found a nice washed up piece of driftwood. They do not want you digging up plants etc.
Do not attempt to order any plant material in from overseas as all is banned unless, as said, you get the biosecurity clearance but this is cost prohibitive.
Thank you for taking the time to check out our laws before attempting any of this :love: