Yalkut Yosef (siman 79 in דין בשר האדם) discusses a minhag brought down by Mar'eh HaYeladim (מערכת ה' אות י) which says:
"it is a segulah for a woman to become pregnant [with a boy] if she takes from the foreskin of a baby [at a brit], dip it in honey, and swallow it".
Leaving aside the discussion of whether this is permissible or not (see the Yalkut Yosef, who struggles to find a side to be lenient, although there are technical reasons that few may say its allowed but certainly not desirable), does anyone know the original source for this minhag and the reasoning thereof?