The reading for this one, like the meaning, is kind of strange. It's the kun'yomi readings, so apologies in advance for that. You have うめ plus ぼし, which comes from 干す though the し is stuffed inside the 干 for some reason. It's also rendaku'd. Basically, everything is all screwed up, so you know, deal with it. This food is awesome, and common, so you have to learn it. I guess the pickling process has mangled the reading of this word. At least it tastes good.
Umeboshi is good for motion sickness.
Umeboshi can be mixed with anything.
Excuse me. May I get through? I’d like to buy that jar of pickled plums.