Plums, if they are green, unless seen on trees, are signs of personal and relative discomfort.
To see them ripe, denotes joyous occasions, which, however, will be of short duration.
To eat them, denotes that you will engage in flirtations and other evanescent pleasures.
To gather them, you will obtain your desires, but they will not prove so solid as you had imagined.
If you find yourself gathering them up from the ground, and find rotten ones among the good, you will be forced to admit that your expectations are unrealized, and that there is no life filled with pleasure alone.... Ten Thousand Dream Interpretation
Green plums forecast sickness; ripe ones are fortunate ; to dream of picking them from the ground and finding them rotten denotes false friends, poverty and disgrace. (Raphael). ... The Fabric of Dream