castor bean fruit
This is the fruit of a castor plant, or castor bean plant, Ricinus communis. I enhanced the contrast a little with The Gimp. The plant grows quite large, taller than I am, and the fruit is roughly the size of a table tennis ball. The plants are grown as ornamentals, and castor oil is derived from them. So is ricin, which is a poison.
Larger sizes are available.
To see a photo of an entire plant, go here. You can see less mature fruits in the right foreground, and elsewhere.