Pipeweed:

An herb grown by the hobbits.
All the same, observations that I have made on my own many journeys south have convinced me that the weed itself is not native to our part of the world but came northward from the lower Anduin, whither it was, I suspect, originally brought over the Sea by the Men of Westernesse. (LOTR.21)

The "art" of smoking pipeweed spread from the hobbits to Men, Dwarves and Wizards most likely through Bree. The true pipeweed was discovered and first grown in the Shire by Tolbold Hornblower.

The Party Tree:

A tree in the field behind Bag-End. At Bilbo's 111th birthday it was enclosed in the family pavilion. It was covered in lights and after dinner, Bilbo spoke his farewell speech under it. The Party Tree, as it was know afterwards, was cut down by Saruman and the ruffians he had brought in to the Shire in the year 3019. Sam planted the seed he was given by Galadriel in it's place and there grew the only Mallorn between the Misty Mountains and the Sea.

The Lord of the Rings
The Silmarillion
The Unfinished Tales
The Hobbit
The Complete Guide to Middle Earth by Robert Foster