I cannot recall much about the book. I know the main character is a boy and he lives in a world that is divided between four factions, each supporting a core element. The story opens at the funeral for the boys father and he meets a man that later hatches a plot to over throw the ruling fire people. He wants to install people from all 4 elements. Also they call the earth element Oaks.
Tales of the Branion Realm looks to be a potential match. The four elements are named "Flame, Wind, Sea, and Oaks". here's a plot summary from TV Tropes:
The island kingdom of Branion is ruled by the DeMarian royal line, whose founder Braniana conquered the realm roughly 900 years before the first novel takes place. She also became the first Vessel of the Living Flame, an elemental being worshiped as a god, which has affected her descendants to the point that they all have fiery eyes that denote their divine right and power. The other three elemental powers are also worshiped, to a lesser extent, and are called the Holy Triarchy, so that the worshipers themselves are called Triarchs. The Flame also powers Seers. A rival faith, Essussiatism, also features prominently and is basically an ersatz Catholicism. The series follows 400 years of Branion history, as the monarchs strive to master their birthright. This is more difficult than it sounds, as having a fire god inside you is not good for your sanity.
And a summary of the first book, The Stone Prince from Amazon:
Crown Prince Demnor must struggle to master the power of the Flame, a magic weapon with a mind of its own, in order to do battle with the rebellious Heathlands and win his independence from his dominating mother.
The Golden Sword by Fiona Patton. The 4th book in the Tales of Branion Realm.
Camden DeKathrine is expected to be the perfect Branion Sword Knight, dedicated to the realm's ruling Avatar of Flame. But instead, claimed by the Aspect of Wind, he is being drawn into the heart of an ancient heresy which will challenge the power of the Living God. And on the eve of the five hundredth anniversary of DeMarion rule in Branion, the centuries-old conflict threatens to destroy not only Camden and his comrades but the entire Physical and Prophetic Realms...