As a native speaker, I too become confused with the sentence, provided with unclear context. But looking at the equivalent sentence in English, it all the pretty make sense. I want to add : The fact that the speaker are owning them becomes useful to the volcanoes and the flower (maybe he/she took good care of them ?)

From what I understand, in English, this sentence would be: As for my flower and as for my mountains, there is a use for me to have them. (If put into more correct English, '...it is useful for me to have them'.) The subject of the sentence is not quite clear because the structure of this sentence is a little bit off. Did this sentence come from literature or poetry, perhaps? I would say that the subjects here are 'gunung-gunung' and 'bunga' since they are the things that are useful to have (being described/acted upon). Hope this helps!

Actually i bit confusing with the setences, but i think it's "I owned it"