I believe that the dreamer best knows the significance of their dream, and, often, by telling your dream to someone, you come to understand it. I am sure that all the meanings you would think of are positive!
However, it is also possible that your soul was wandering a little during sleep and saw the plum tree at a higher level of reality in an ideal or perfected form - that is, what it would look like if it were not subjected to the imperfections and decay of this world. This might also be why you remember it strongly. This is similar to how, in Paradise (inshallah), when we see a person or an animal or a plant, we will see it in its ideal and perfect form without the defects that they have in this world.
It is a nice dream anyway!