In a comment on a journal entry a few years back, Sarah P introduced me to the term "mullygrubs," which turns out to be an alternate spelling for mulligrubs, which Quinion defines as "A state of depression or low spirits" and Dictionary of American Regional English defines as (among other things) "A condition of despondency or ill temper."
It can also refer to a stomach ache or a particular kind of ball in cricket. Apparently the word appeared (among other places) in Steinbeck's Travels with Charley.
Quinion also mentions the word "megrims"; a megrim was a migraine, but "megrims" could mean just general low spirits. I'd heard that before, but had forgotten it. Quinion and MW3 suggest that "mulligrubs" might even have originally been an alteration of "megrims."
Anyway, "mulligrubs" isn't quite a new-to-me word, but Sarah's mention of it was my only previous exposure to it, so it was new to me a few years ago; close enough for blogging.