Osage oranges, a.k.a. hedge apples (Maclura pomifer) are the coolest looking fruits I've ever seen. They look like wrinkled little chartreuse brains, or maybe, from a distance, bright beaded balls. Really, you'd never believe they grew on a tree if they didn't have such a sharp citrus scent - which is rumored to repel spiders and other insects.
Native to Texas and Arkansas, the trees are harvested for their yellowish-orange wood which makes fine fenceposts and musical instruments. Native Americans used the wood for bows. When the trees are planted close together, they form an impenetrable, thorny hedge ideal for keeping livestock from roaming.
You don't want to cut open osage oranges, because they're pulpy and slimy inside - even squirrels and other rodents ignore them. I love the theory that their seeds were originally dispersed by a giant sloth species that was able to survive eating their mildly poisonous pulp.
Osage oranges are remarkable looking...see for yourself in the bowl below. The glass pumpkins are by Whidbey artist Robert Adamson; the osage oranges were gathered in Yakima by Lorene Edwards Forkner, who kindly gave me some after I drooled over the big tray of them on her dining room table.