Hi JC!
Tomatoes, tomatoes, tomatoes!!! In my garden at home (Southern San Joaquin Valley of California, Zone 8b or 9, depending on who you ask) I have 5 different varieties of tomatoes planted, and they do extremely well in these long, hot Summers! I have Heirloom Black Prince, Heirloom Brandywine, Sweet 100's, Big Boy Beefsteak and Roma tomatoes. And those are just the ones in my vegetable garden....don't get me started on the hand-me-down seeds offered by friends and family, which are of unknown varieties and planted in window sills, flower beds and scattered willy-nilly about the property!!
I also have a virtual forest of Zuchinni, which grows exceedingly well here, and doesn't require any special treatment except a bit of elbow room and the occasional bee. Cucumbers, also, do remarkably well in this climate, and the butterflies and bees love the yellow blossoms. I have standard Zuchinni, and Russian Lemon zuchinni right now.
You mentioned that you were renting the property, and didn't want to expend a lot of effort improving land you don't own...and I undertsand that. That's where container gardening can be your best friend!!! Many, many varieties of flowers and vegetables can be successfully grown in containers, even on apartment balconies, rooftops or fire escapes. Brussels Sprouts, Cucumbers, Pole Beans, Green Beans, small melon varieties, berries, carrots, peppers, turnips, etc, etc.... The list is vast, and varied enough to keep you in fresh vegetables all year long with minimal effort (and no digging). The best part is....if/when you decide to move, you can take your garden with you!! In addition, those varieties which don't like the heat/cold can be moved inside/outside as the weather changes. And don't forget about fresh Herbs!! Not only are they very fragrant and tremendously useful to have in the kitchen, but many, many of them are also quite beautiful when used as simple house plants or color/contrast items in a flower container. Amethyst Basil (the purple basil variety) is awesome when planted in the center of some French marigolds! Lettuce and cabbage, too, can be quite ornamental. The flowering Kale varieties, for instance, are not only striking in appearance, they're tasty as well!
My best advice for the renting gardener is to use raised beds which will allow you to plant pretty much anything, anywhere, without disturbing your landlord's landscaping or popping through a sprinkler pipe. A couple of 4-walled wooden boxes (which you can make yourself with a hammer and nails), a few bags of rich potting mix, and off you go...
Whatever you decide to do, I wish you the very best of luck. There are very few things in life which prove to be as soul-satisfying as growing living plants, and reaping the benefits from your own labor. I truly believe that, once you get started in Gardening, you'll find a whole other world out there that you have been missing.
Good Gardening!
Chris