It was a small vial of am unknown elixir. She thought of returning it, but instead, she impulsively quaffed the mysterious substance. Stones started to randomly appear and crumble to dust. As this strange event wore itsef down to subtility, she began to learn how to create and shatter stones, with the power she doesn't even think is magic.
So then i might only have:
Conjure rock, roll for size.
Dispel stone, shatter a physical fom, or an escence of stone.
So Tyu has specific stone-related magical powers that are one-off? Essentially along the lines of a feat? I think I can allow that, but I'll need to check up the rules on adding spell-like abilities.
Edit: Couldn't find any, but why put all those years of Homebrews on the GITP forums to waste?
You have three spell-like abilities, listed as below. They take the place of your initial feat(s) and are probably unbalanced, but I'll let it go since you're a Commoner.
Pebbles 3/day - You shut your eyes, put your hand to the ground and find three stones, each no larger than an apricot stone. These stones, when thrown or hurled with a sling, deal 1d6+1 damage (including an effective +1 modifier to attack).
Stonesplitter 1/day - Speaking an oath in the name of God, you utterly shatter either a single immobile rock, crystal or metal ore or stone/crystal/ore within a 5ft radius.
Summon Stone 1/week - You must be below a ceiling or close to a cliff or other rock 'wall' for this to work. A rock of variable size (Small or larger - roll 1d6-1 and increase the size appropriately) will fall from the ceiling or toward an enemy. You may direct its initial fall as an unmodified (straight d20) attack roll.
Following the initial turbulence after imbibing the potion you prayed to God in desperation, promising Him that if He would keep this terrible curse at bay you would use it only in His service. That night, the power vanished almost to nothing in your sleep. Since then you have only been able to recall it by prayer or meditation in God's name.
Double Edit: Also, you will likely want to pick skills and equipment.