Low FODMAP fruits with a greater ratio of glucose to fructorse include Bananas, berries such as blueberries, raspberries and strawberries; citrus fruits; some exotic fruits such as jackfruit and tamarillo. However, since fruits are still recommended in restricted portions on FODMAP diets, go for bananas which have higher carbs for a smaller serving. You could also try the aforementioned fruits dried.
Starchy root vegetables you can try: carrots, parsnips, sweet potatoes & yams of all kind (predominantly glucose), swede, squashes such as butternut;
White rice: though we avoid grains, especially gluten grains, white rice is basically a pure starch, with most of the aninutrient chemicals and possible irritants removed with the rice bran (phytates, lectins, fiber - which can irritate a sensitive gut). Some people on paleo eat rice for their starch; now its nutritionally inferior to root vegetables, even to white potatoes, so I wouldn't recommend it (as I wouldn't recommend any low-nutrient 'dinner plate filler' which basically displaces other, more nutrient dense foods you could have eaten), especially if you are already on a restricted diet. However, if you really have IBS to the extent that you can't tolerate most root vegetables (you didn't give details on that so I don't know), white rice is something you could consider. It does have some potassium, magnesium, niacin, thiamin and iron, to give it merit. Remember that we avoid grains because of the harmful substances (e.g. gluten) that they contain, not because they are called 'grains' and do not fit into dogma.
Quinoa is also a grain alternative (its actually a pseudo-cereal, not a grain, and a relative of green leafy vegetables such as chard, similarly to buckwheat, which is related to a grass); it doesn't contain gluten and is higher in protein and nutrients than white rice, but also high in carbs so its an option if you want to increase those in your diet; just make sure you rinse the quinoa before cooking to remove bitter saponins.
Hope I helped!
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