Tomato, eggplant, potato - all are members of the Nightshade (Solanaceae) family. Not all Nightshades are edible, though. Some are downright nasty.
As with anything you find outside, don't eat unless you know for sure what it is, And don't take Paul's word for it; he tries everything!
Although tomatoes aren't normally found in Sabino Canyon, Patricia and I noticed this plant while on the lizard walk of 6/15/2010. My Honey-Matt took the photo on 7/3/2010 (and I used it as part of the first ever post on this blog, 7/4/2010). It was located in a nice picnic spot by the dam. Seed from a slice on a sandwich, perhaps?
You know the drill! Note that the flowers have fused petals, i.e., you can't pluck one individually.
Tomorrow, a plant called Hairy Five Eyes! (Yes, a Nightshade.)