I can only ever recall finding zoned polypores on leylandii stumps. Can't remember finding anything edible on them. Doesn't mean it can't be done, though.
I'm racmking my brains for a use for the lleylandii, there's definitely summat you can do with 'em
Other than as hedge or shelterbelt, PFAF has nowt.
Of course, the wood is soft cypress and should be really easy to work.
And you often find wood blewits growing under them, so chipped it should be a good substrate for growing those guys on. Make a good woodchip mulch I'd have thought.