How we cite our quotes:
But we looked into a fire, we leaned across a table,
We lay on a hill-top underneath the moon;
And the whistles kept blowing, and the dawn came soon. (3-6)
The speaker emphasizes the "we"-ness of the actions she remembers, making sure that the reader knows that everything that happened that night was done with "you."
We had gone back and forth all night on the ferry;
And you ate an apple, and I ate a pear, (8-9)
The syntax of line 9 feeds into the sense of shared actions set out in lines 7 and 8: the repetition of "and" allows the speaker to describe each individual's actions as if they were part of a related whole.
We hailed, "Good morrow, mother!" to a shawl-covered head, (15)
The casual use of "mother" here signals a sort of kinship and respect which is actually more like friendship than actual family relations.