I have had a garden most of my life; from the family garden as a kid to a 15x40 plot I gardened far many years to my sorry postage stamp plot now.
I've always gotten a lot of satisfaction from it as well as much good fresh produce. Welcome to a great hobby!
Go here:
http://rareseeds.com/shop Baker Creek Heirloom Seeds
They offer a sweet variety of heirloom seeds that will really whet you appetite for gardening. Ask them to send you a catalog - one of the most beautiful books you'll ever read (OK - so maybe that's a bit of an exaggeration, but not by much!). I wore mine out in four days reading plant descriptions and looking at pictures (better than Playboy - except for the melons!)!
Most seed you can buy locally for half the price, but the selection here will just WOW you.
This year I ordered, among other things, Green Zebra Tomato, Lemon Hot Peppers, Chinese Red Meat Radish and Mexican Sour Gherkin Cucumber.
I cannot wait for spring.
**disclaimer - I have no financial interest in Baker Creek - just love to send them money!**
Tomatoes alone, fresh from the vine, are worth the gardening effort. Unlike most plants that you should plant at the same depths as in their starter pots, you should plant your tomato plants DEEP. If your plant is 12" tall strip of the lower leaves and dig a hole deep enough to leave only 4" or 5" above ground level. When the ground and nightly air temps warm up your plants will grow like weeds with all that stem putting out additional roots. And speaking of weeds, you can eat the lambs quarter that WILL find it's way in to your garden.
Cherry Tomatoes (I like Supersweet 100) are great for salads or just snacking off the vine. Unless you have a huge family, plant only two (and that's just so you have a spare in case something happens to the first) because they are so prolific.
You don't really have room for sweet corn but if and when you do it is fun if for no other reason that for the plethora of varieties available to grow other than the "Honey and Cream Super Sweet Blah Blah Blah" you see at EVERY market.
Potatoes are fun when you dig them and discover what's been growing under there all season. But potatoes are so cheap all year long I can see much more productive use for my garden space. Grow a couple plants for fun but don't exclude other vegetables just so you can stock up on $20 worth of potatoes!
Edible pod peas are a delicious early crop. As are radishes.
I like to eat spinach but don't find it worth growing as it takes a lot of space to grow enough as it cooks down so much.
If you like salads, try an assortment of leaf lettuces, greens and things like Pak Choy.