Commoners give common gifts.
Just because this paladin is high level doesn't mean he no longer needs common things. He still eats, sleeps, bathes, has dirty clothes, etc.
I guess we need to know who this commoner is? Is she a peasant farmer? Then a home cooked meal might be appropriate, as well as some fresh provisions, or even a pack animal. A mule isn't exactly a noble steed, but it has a strong back and can carry loot back to the temple.
Or mabe your commoner is a seamstress. Surely this paladin has torn and bloodstained clothing that needs mended? After days of travel, his garb must be covered in road dust. Clean clothes, new socks and undergarments are practical for everyone, and would be much appreciated IMO.
If this commoner actually runs a tavern or inn, then she's sure to have some hard to find foodstuffs. Maybe a piece of citrus fruit, or some fine sugar she can make an elaborate dessert with. Maybe some period inspired handicrafts? A clove pomander to keep foul odors away from his pack. Some home-made cake soap? Cleanliness is next to godliness after all.
If this peasant has some woodworking skill then perhaps a gift to the temple might be appropriate. A carved wooden altar, or kneeler, or even a simple devotional item, or holy symbol.
Maybe the commoner offers to clear a patch of land, and establish a small roadside shrine to the paladin's patron? Or the land is given to the temple to provide for the brother's needs?
Think about the phrase "killing the fatted calf" whatever the commoner has that is best will be served up to this noble champion. And, as a LG holy warrior, he should thankfully accept it in the same spirit it is offered.
And just becase he's rich, magical and mighty doesn't mean he's forgoten the simple pleasures of a full belly, clean clothes and a good night's sleep.