basically already thought of the same thing, using the athas.org druid for spells known, but adding ritual casting based on "spells and spellcraft"(from FFG). . . basically you've a list of spells you can cast inately as a part of your character's connection with nature, but still have access to utiliy spells. . . as long as you have the time and make the spellcraft rolls. . .
some examples:
Detect Plants and Animals
The character can detect a particular type of animal or plant in a quarter circle emanating out from the character in whatever direction the character faces. The character must think of a species of animal or plant when using the spell. Each round the character can change the animal or plant type. The amount of information revealed depends on how long the character searches a particular area or focus on a specific type of animal or plant:
1st Round: Presence or absence of the animal or plant type in that quarter.
2nd Round: Number of individuals of the specified type in the area, and the condition of the healthiest specimen.
3rd Round: The condition and location of each individual present. If an animal or plant is outside the character's line of sight, then the character discerns its direction but not its exact location.
Conditions: For purposes of this spell, the categories of condition are as follows:
Normal: Has at least 90% of original hit points, free of disease.
Fair: 30% to 90% of original hit points remaining.
Poor: Up to 30% of original hit points remaining, afflicted with a disease, or suffering from a debilitating injury.
Weak: 0 or fewer hit points remaining, afflicted with a disease in the terminal stage, or crippled.
If a creature falls into more than one category, the spell indicates the weaker of the two.
Note: Each round the character can turn to detect things in a new area. The spell can penetrate barriers, but 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt blocks it.
The DM decides if a specific type of animal or plant is present.
Caster Requirements: 1st level spell
Time Requirements: 1 hour
Place Requirements: outside
Material Components: none
The Ceremony: The druid prays and sings while visualizing the desired plant or animal and stretching out their minds to reach out through the Long range area
Ritual DC: 10
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Call forth the Sky's Fury(call lightning)
One of the only pure war ceremonies this calls down lightning from a storm once every ten minutes, directed by the druid and doing 1d10/caster's level (max 10d10) The druid can call down a maximum of 1 bolt/level without having to reinfuse this ceremony with spell energy.
Caster Requirements: 3rd level spell
Time Requirements: 1 hour
Place Requirements: stormy area
Material Components: a drum made from the skin of a creature that died from electrical damage.
The Ceremony: The druid plays the drum as the targeted storm gathers energy(the storm is extended by the energy of this ceremony if it would fade before then) the druid must keep playing the drum as he calls down the lightning to strike his foes.
Ritual DC: 15
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Communicate with Plants(speak with plants)
This ceremony enables the caster to hear and understand the murmering of the trees and the whispering of bushes and enables them to ask questions from the nearby plants.
Caster Requirements: 3rd level spell
Time Requirements: 15 minutes
Place Requirements: none
Material Components: none
The Ceremony: The druid sings softly and quietly to the plants he wishes to hear then listens silently to the platns, continuing to sing in druidic then listen to the plants reply throught the duration of 1 minute/caster's level
Ritual DC: 15
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Nectar of Flowers
Often used to provide drinks for celebration, a gift, or just for relaxation, it is viewed as taboo and to be very bad luck to actually sell the results of this spell for money, receiving 'gifts' or 'favors' for the results of this ceremony is more acceptable though
Caster Requirements: 1st level spell
Time Requirements: 9 minutes
Place Requirements: none
Material Components: the flower
The Ceremony: A druid who casts a nectar ceremony on a flower is able to grasp it in his hand and "milk" it. Up to one quart of nectar can be produced from a single flower. The plant upon which the flower grows must be living. The nectar is mildly alcoholic, and has the flavor and fragrance of the plant from which it is produced. The nectar itself is of the same quality as a fine wine. A receptacle held beneath the flower can be filled with the nectar. Otherwise the caster can simply hold the flower over his or another's mouth. Those that prize fine drink will appreciate this druid spell.
Ritual DC: 10