Which encounter does Odysseus and his men have before Polyphemos?
In Odyssey 9, Odysseus tells the Phaeacians about his adventures after he left Troy. Prior to his arrival in the land of the Cyclopes, Odysseus has two encounters.
The first encounter comes at Odyssey 9.1-62. Here, Odysseus and his crew go ashore in the territory of the Cicones. Their initial attack on the Cicones was successful, but then Odysseus' men refused to sail away, deciding instead to drink wine and feast on the cattle of the Cicones. In the meantime, the Cicones regrouped and mounted a counter-attack on Odysseus and his men, who managed to escape, but not without losing about 70 men.
From the land of the Cicones, Odysseus and his men sailed to the land of the Lotus-Eaters. Here, of course, three of Odysseus' men feast upon the lotus plant, which causes them to forget "all thoughts of return" (A.S. Kline translation). Odysseus, however, manages to drag them back to the ships where he "bound them tight in the hollow ships, pushing them under the benches."
This encounter with the Lotus-Eaters highlights one of the major themes in the epic, namely the concept of nostos ("return home"). Odysseus' men forget about their nostos. Odysseus must make sure that he stays focused and does not forget his nostos.