Trees bearing unusual items are a regular occurrence in the Oz series, so it’s kind of interesting that they weren’t really part of Oz as it was first envisioned. The Wonderful Wizard of Oz has fighting trees, but otherwise trees seem to be pretty much what you’d see in our world.
It’s in The Magical Monarch of Mo that L. Frank Baum introduced the idea of trees growing just about anything a person would need, including hats, rings, swords, bicycles, caramels, peanuts, shrimp salad, tarts, and animal crackers. Rather disturbingly, the latter can turn sentient and argue over which deserve to be eaten. Then, in Ozma of Oz, Dorothy finds lunchbox and dinner pail trees in the Land of Ev.
Emerald City mentions that the trees in Bunbury produce doughnuts, but it’s really in Patchwork Girl that such trees seem to be commonplace in Oz. Ojo and Unc Nunkie have a bread-tree that stops blooming, and when they visit Dr. Pipt, his garden contains “bun-trees, cake-trees, cream-puff bushes, blue buttercups which yielded excellent blue butter and a row of chocolate-caramel plants.” In Tik-Tok, the people of Oogaboo take the names of their crops, which range from apples and plums to banjos, nails, and clocks. There’s also a tree that bears guns.
In addition to his files, Jo Files grows book trees, the fruit of which start out green but turn red when they ripen. If you read an unripe book, the stories and their spelling and grammar will be bad. They also shrivel up after being read once. In the same book, we learn that the Nome Kingdom has trees that bear nuts with three-course meals inside.
Later Baum Oz books occasionally mention such trees, and Ruth Plumly Thompson brings in even more. She even exports the phenomenon to Ix, with its Box Wood in Silver Princess.
Indeed, while never actually stated in the canon, it’s a popular theory among fans that pretty much all meat in Oz grows on trees, so that the morality of cooking talking animals can be avoided. So where do all these trees come from? Some of them seem to just grow wild, while others are cultivated, but we’re never actually told how, say, a clock tree is grown. Would planting a clock or part of a clock be enough, or is there more to it than that? I’m reminded of the just-created Narnia in The Magician’s Nephew, where an iron bar grows into a lamppost and coins into metal trees.
In Cowardly Lion, the characters come across a Travelers’ Tree, on which covered dishes, cups, and pots of hot drinks grow. A sign indicates that the tree was planted by the Wizard Wam, who would later resurface as the creator of the wishing necklaces in Wishing Horse. Another sign tells those eating from the tree to plant their dishes after finishing. In Henry Blossom’s non-canonical Blue Emperor, Wam accuses the Nome King of stealing the idea of his Travelers’ Trees for the Hotel Trees that bear the three-course nuts. And it might not be too much of a stretch to think he could have planted the lunchbox and dinner pail trees for the royal family of Ev as well. In Melody Grandy’s Seven Blue Mountains trilogy, we meet Wam’s son Zim, a sorcerer and botanist who can grow just about anything on plants.