Another poem my mother likes to quote is "Trees" by Joyce Kilmer (1886-1918). It's not so long as Longfellow's "A Psalm of Life". With a little work, I might even be able to master this one!
I think that I shall never see
A poem lovely as a tree.
A tree whose hungry mouth is prest
Against the earth's sweet flowing breast;
A tree that looks at God all day,
And lifts her leafy arms to pray;
A tree that may in Summer wear
A nest of robins in her hair;
Upon whose bosom snow has lain;
Who intimately lives with rain.
Poems are made by fools like me,
But only God can make a tree.
-- This was originally published in Trees and Other Poems (Joyce Kilmer. New York: George H. Doran Company, 1914).