My guys pretty much love everything except bananas. They regularly get all the overly ripe apples, pears, strawberries, peaches, pineapple, watermelon, etc. that we have. They also really like cucumbers. I grew some last summer and had way to many to eat or get rid of and the horses sure loved munching on them!
Our previous pony would eat almost everything (granola bars, chicken, dog food, liver biscuits, etc.) but didn't like Corn Nuts? Our current pony eats corn nuts, even the spicy picante flavor, guacamole Doritos, candy, the other day he ate part of my turkey sandwich!!
My horses are more picky than the pony.
Just remember that although peaches are OK for horses, peach trees are not (cyanide in leaves) and fresh corn can carry some sort of spores like botulism.