Smeagol was born Trahald in 2430TA near the Gladden Fields, not far from the Anduin River where Isildur lost his ring. He was part of a fairly important Stoor Family. When he was 33 (his coming of age) in the year 2463, he went fishing with his cousin Deagol ...
Give us that, Deagol My Love
It was probably a nice, plesent day, but there was something black in Smeagol's heart that made him do what he did. You see, Deagol spotted something glittering in the water, and went to pick it up (In the movie he fell into the river cos of a big fish). And it was, you guessed/knew it, the One Ring.
The moment Smeagol saw it, he knew he must have it. He begged and pleaded Deagol, saying that it was his birthday and Deagol still owed him a present. In the end, he got so angry with Deagol that he murdered him. His very own cousin.
My Preciousss ...
And so everyone hated poor Smeagol. They bullied him, and eventually drove him out of the Gladden feilds. From there, he went on to live in his cave, and there he stayed for about 500 years, until Bilbo came and "stole" the ring, and well, you know the rest from there.
