Arcane spell casters have rings of sourcery and wizardry, clerics have rings of divinity, would it be possible to have rings of the woodlands for rangers and druids? Rings would be made of wood equivilant for each level oak for lvl 1, mahog for 2, yew for 3 granting maybe 1 or 2 spells for each appropriate level. Other components would be the same as their divinity counterpart.