Is there a verb or phrase for "good-morninging" someone?
Solution 1:
"Good-morning" is not a verb in common use in English. I checked a couple of dictionaries and it isn't in there. It also doesn't occur (as "good morninged" with or without the hyphen) anywhere in the books used as the corpus of Google NGram.
So this was just a unique coinage that Tolkien used for comedic effect here. Of course the meaning is plain because English nouns do "verb" very easily. But it is a deliberate figure of speech, in this case a coinage, to draw some emphasis for a little comic relief.