Colour of Magic and The Light Fantastic
The first two Discworld novels in one volume. The Colour of Magic introduces Rincewind, a spectacularly incompetent wizard, and Twoflower, the Disc's first tourist, along with the Luggage, a sapient travelling chest on many small legs. The Light Fantastic continues the same story directly, which is why the two are often bound together. These are the most parodic Discworld books, closer to send-ups of fantasy convention than the sharper social satire Pratchett developed later.