While translating the Tom Sawyer comic book, I found that Becky recites the first three lines of this poem:
If Ever I See
by Lydia Maria Child
If ever I see,
On bush or tree,
Young birds in their pretty nest,
I must not in play,
Steal the birds away,
To grieve their mother's breast.
My mother, I know,
Would sorrow so,
Should I be stolen away;
So I'll speak to the birds
In my softest words,
Nor hurt them in my play.
And when they can fly
In the bright blue sky,
They'll warble a song to me;
And then if I'm sad
It will make me glad
To think they are happy and free.