You don't need an official to tell you about items that are listed in the first post of the thread in order to find them. They can be claimed at any time
while on that route as long as you fit the requirements (if any). To claim one of the listed items, simply have your trainer notice the item somehow, in the same way as when an offiical says you found stars or an item during a random event!
Sarah walked over and noticed something shiny on the ground. Picking it up, she realised it was TM66 Payback. "I wonder who left this here?" she thought.
Sarah obtained TM66 Payback.