No matter if not bruised or spiked with stubble, Went surely to the cider-apple heap As of no worth. (lines 34-36)
OK, we'll just lay out our cards on this one: the fallen apples seem to us like fallen people, or sinners who have lost their dignity along with their grace. Frost seems to feel sympathy for the fallen apples and, by extension, fallen mankind.
One can see what will trouble This sleep of mine, whatever sleep it is. (lines 37-38)
The speaker will continue to be haunted by similar thoughts all night long, except he won't exactly realize it, being asleep. We think the word "trouble" is a fitting word when you consider all the subtle references to sin and the Fall of Man.