Sugar cane has the most acreage on the northern and western sides of the main islands (the dryer sides). The eastern and southern parts of the islands grow a lot of different crops, including taro root, ginger, papaya, coconut and mahogany. Most of the mountainous interior is rain forest where some wild fruits can be found, including "kavika" (similar to rose apple), "wi", "ivi nut", and wild yams.
The volcanic soil here is very rich. I had read that the soil contains a lot of micronutrients because it is created directly from the earth's magma that is rich in trace minerals. In contrast, sedimentary rock has more separation of minerals based on density over the millenia.