This first picture is of the small fenced off are where I have planted 8 broccoli plants and 8 cabbage plants. They're back behind other plants. I had to work a bit to even get a good picture where you could see them, and even in this one they aren't all that visible. There is also a row of beets and one of carrots between the others. Broccoli will be ready soon and the cabbages are starting to head. Although I much prefer a pretty garden with nice neat rows of lots of things, this will have to do for this year.
This next one is my cucumber patch, where they seem to be much larger every time I look. Just about to flower and make me some cucumbers that I will turn into bread and butter pickles. The whole patch is about 6 feet by 10 feet. Plenty of space for a lot of pickles to grow. I have a short fence around it and netting over the top, rigged up sort of like a circus tent. The baby groundhogs aren't going to get these.
Tomatoes are actually kind of easy to do since you can put one plant (and a fence) in a pretty small space. With this green fencing, it blends in very nicely with the other plants. You really have to look to see it sometimes. I have 6 - 3 Rutgers for Hank and 3 Beefsteak for me. There are green tomatoes on the Rutgers, so not too much longer to wait. These are pretty much for fresh eating. I'll get the quantity I need for canning from the farmers' market.
And if you can't find a place amongst the perennials, just grow your veggies in pots. My peppers just didn't seem to have a good place to go, so I put them in gallon pots, and already have a pepper growing.
There are also plenty of 'grow them on the patio' types of containers for vegetables, so unless you live in a closet, you really don't have any excuse for not having a fresh tomato or 2 this summer that you grow yourself.