It’s at the heart of this debut collection: that which has been left behind, tossed out, put in the trash, given away, or dismissed as no longer useful/valuable/functional.
(Literally “at the heart”, for the author clearly feels a strong emotional connection with the discarded.)
People or objects that have been cast aside: these are the flora and fauna of The Beggar’s Garden.
Don’t let that put you off, however: these stories are not bleak and sorrow-filled stories of the disenfranchised.
Indeed, there are plenty of humourous moments in these tales.
(I have lot more to say about this collection here, if you're interested. It will have a wide appeal, even for those who normally prefer novels to stories.)