Lots of good points here indicating that certain leaf mixes should be reserved for certain animals, or just avoided all together.
I had catalpa trees once, they provided hundreds and hundreds of pounds of food for my goats when they dropped leaves. Elm leaves are popular with the entire farm, and the seeds are edible green or dried. Mulberry is another obvious one, along with willow. I don't know anything that won't eat willow.
If you had a line on fruit tree trimmings you'd be set. Everything from rodents to rabbits to goats to horses love fruit tree stuffs, especially apple. Cherry has some controversy shrouding it; what I've 'more officially' read is that the actual species of wild cherry (Prunus serotina) can have a leaf toxicity if the leaves are consumed while WILTED; fresh or dried is okay. That seems to have been turned into "cherry leaves are toxic". I only know what I've read, so I would do more research. Or just leave it out all together since 'common knowledge' now says cherry leaves are deadly.
The only thing I'd be concerned with, as a consumer, is where were these leaves sourced from and how much herbicide and pesticide and fungicide has been sprayed on them? Are they from a city where the plants are inundated with pollution and air-borne debris? Those are things that matter to me. But I also probably wouldn't buy any pelleted feed for any reason, so my input on that might not be well placed
