Paddle cactus (Opuntia ficus-indica)
Both the fruit and the paddles of this commonly found St. John cactus are edible.
Nopales or nopalitos are the grilled paddles of the cactus. The fruit is also edible, but you have to be sure and get rid of all the spines.
A friend of mine, the Ghost, told me that he knew how to eat the fruit without peeling it first. He ended up with a tongue full of cactus spines and spent the next half hour plucking them out. I know you shouldn’t be laughing at the misfortunes of others, but I couldn’t control my laughter.