The quotation Freud's patient recalls is from German poet Ludwig Uhland's ode to nature Einkehr ('Stop-over').
From 'The Songs and Ballads of Uhland', as translated by W. W. Skeat (original 1815)
A kind and gentle host was he
With whom I stayed but now;
His sign a golden apple was
That dangled from a bough.
Yea! 'twas a goodly apple-tree
With whom I late did rest;
With pleasant food and juices fresh
My parching mouth he blest.
There entered in his house so green
Full many a light-winged guest;
They gaily frisked and feasted well
And blithely sang their best.
I found a couch for sweet repose
Of yielding verdure made;
The host himself, he o'er me spread
His cool and grateful shade.
Then asked I what I had to pay,
Whereat his head he shook;
blest be he for evermore
From root to topmost nook!