The only thing mentioned in the novel that Tom buys for Myrtle is the puppy. Myrtle herself buys the other things. The only Tom has given her is the puppy and pays for the apartment in the city, where the two of them meet for their affair. This apartment is where they have the party and Tom ends up breaking Myrtle's nose. Nick is introduced to all of this in chapter two.
Tom is selfish. We see this by many means. First is that he is having an affair, while both of them are married to other people. With the physical abuse that Myrtle gets from Tom, also goes to show how selfish Tom can be. Yes, he pays for the apartment for Myrtle, but it is only so he can meet her there, so it is for his benefit. We also begin to see the first glimpse into the man that Daisy married. He is wealthy and uses his money as a way of flaunting what he has. By buying these couple of things for Myrtle, he is making sure he can keep her on the side. Myrtle, on the other hand, sees it as his love for her, but we all know he doesn't love her, he is only using her.
By seeing into the character of Tom, we begin to realize how far he will go to get what he wants. He doesn't care who he hurts, just as long as comes out looking like the winner. Jay Gatsby threatens all that Tom is and Tom is not going to allow anyone to take away what makes him look good and look successful. In chapter two, we are given glimpses of Tom's true nature and we are being prepared for the tragic outcome of the novel.
Tom purchases "a gossip magazine and some beauty aids" for Myrtle when they go into New York City. He also pays for an apartment in the city for her. He even buys various clothes for her--one dress is the one she changes into for her party the night Nick was with them.
Actually Myrtle buys herself those items: "At the news-stand she bought a copy of Town Tattle and a moving-picture magazine, and in the station drug-store some cold cream and a small flask of perfume (p. 25)." Besides the puppy and the apartment, it is never discussed what else Tom buys for Myrtle.