From an old post of mine on uk.music.folk:

I was trying to find a song where a a sadistic woman gets a boy
to cut his mother's heart out to feed her dog, when he falls and
drops it on his way to her, the heart calls out asking if he's
all right.

I got the nationality wrong. The song is by the 19th century
French poet Jean Richepin, ultimately from a Finnish ballad,
and the translation I was thinking of was by Herbert Trench.
There is a choral setting of it by Joseph Charles Holbrook,
who I hadn't heard of before.

   Jean Richepin's Song
   ====================

   A poor lad once and a lad so trim
   Gave his love to her that loved not him

   And says she, 'fetch me tonight you rogue'
   Your mother's heart to feed my dog!

   To his mother's house went that young man
   Killed her and took the heart, and ran.

   And as he was running look you he fell
   And the heart tolled to the ground as well.

   And the lad, as the heart was was a-rolling heard
   That the heart was speaking and this was the word

   The heart was a weeping and crying so small
   'Are you hurt my child, are you hurt at all?'

Hamish Henderson's translation isn't in his Collected Poems and
Songs. Where was it printed? I know I've got it somewhere.

The first tune that came into my head for Trench's text was
"Blyth, blyth, blyth was she", but lots of others would fit.
Henderson's doesn't have such a singable metre.

I prefer Trench's version by a long way.