Fey creatures reproduce through using feyfire mushrooms. These mushrooms, however, are increasingly rare. They can reproduce naturally in the wild, but the only known sources are far distant in the Mwangi Expanse. There may be some growing in a university in Cheliax, however.
Chess Rivkin, an adventuring wizard, took all the feyfire mushrooms from the Wasted Lands. It is unknown where he went, but some suspect he went to Numeria.
feyfire mushrooms may be created through sacrificing children to create the foods.