Who does he sound like?
 

I don`t know if this has been asked before or not, but it has been bothering me for quite some time. In The Two Towers where Frodo and Sam are having an arguement
Who is Sam talking about? My guess it`s Gollum. (Mine! My own!) But I`m not sure. Who else could it be? Boromir? Isildur? What are your thoughts?

Gollum is the one that jumped out to me, & I think that's who PJ is insinuating Frodo is beginning to sound like. At any rate it couldn't have been Boromir, because he never said it was 'his', since he hadn't ever possessed it.

I'd say it's Gollum. After all that is who Frodo sounded like most just then.

When Frodo said
I half expected him to add "My Precious!"

I also think that it was Gollum.

Yes, I also expected him to add "my precious" to that.

I thought it was Gollum Sam was talking about, but I wasn`t quite sure. :p

Sounding like the ring.
 

The reason why Frodo sounds this way is because the Ring affects its bearers in hte same way, giving a real persona to the vice we call greed.

Sam, on the side of it, associates this tone to Gollum, since he has only heard Gollum. Boromir was alone with Frodo when He talked this way, and Sam was nowhere near Isildur in time or space to hear the king.

Although Sam's speech to Faramir in Osgiliath (in TTT) would indicate that Frodo had told him of his encounter with Boromir. Still, Boromir never used those words, so you're right that Sam couldn't have been speaking of Boromir when he was talking to Frodo.

Oh, I overlooked that. Thaks, Esty !

Yes, I was going to say that Estel. The reason why I thought Boromir could have been who he was talking about was because of how he said, "It could have been mine! It should be mine!"

What about Bilbo? At the beggining of FOTR he says;

Although it is different words, it's the same spirit, the focus on 'me' and 'mine'.

That's true, Arwen Imladris; but I doubt that Sam would've known of the conversation. It seems unlikely that Gandalf would've spoken later of what happened, except maybe to convince Frodo of the power of the Ring. In which case I don't think Frodo would've felt the need to tell Sam about it, certainly not down to the very exact words. Still, you never know :D.

Gollum