Sarn Ford:

A ford to the south of the Shire.

Sarn Gebir:

A dangerous area of rapids in the Anduin River. Sarn Gebir was near the Gates of Argonath and the Emyn Muil. There was a path around the rapids surviving into the War of the Ring.

Sirion River:

A river in Beleriand, the Sirion was over 130 leagues long from springs to mouth.

Sammath Naur:

The Chambers of Fire, within Orodruin. This was where Sauron forged the One Ring and where at the end of the War of the Ring, the Ring was destroyed.

Southfarthing:

One of the five regions of the Shire at the time of the War of the Ring. The other areas were the Northfarthing, Westfarthing, the Eastfarthing and Buckland This is the southernmost area of the Shire. The Tower Hills were added by the decree of the King sometime in the early Fourth Age.

The Shire:

Located in the North-West of Middle-Earth, this is the country of the Hobbits. It was ceded to them by Argleb II in the year 1601 of the Third Age of the Sun. Originally consisting of four areas that they called Farthings, which were the Northfarthing, Westfarthing, Southfarthing and Eastfarthing. Later the area of Buckland was added to the Shire. By the decree of King Elessar, early in the Fourth Age of the Sun, the Westmarch, including the Tower Hills was added to the Shire. By the decree of the King, no Men were to enter the Shire at all. Only two battles were ever fought in the Shire: The Battle of Greenfields, fought against orcs, in 2747 and the Battle of Bywater at the end of the War of the Ring in 3019.

Many areas of the Shire are named for families prominent in that region, such as the Tookland or Buckland. However, other than in those two cases, where the families still lived mostly in that region, hobbit families had spread to the rest of the Shire.

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