Gregg, a 6x6 space can have a lot stacked into it. You could have one or two mini-dwarf or columnar fruit
trees in large pots (so you can take it with you) at the back (north side) of the bed, a bunch of
perennial greens that will give year-round food in milder climates (down to 25 F or maybe less), such as bush collards, good king henry, New Zealand spinach (those all taste a lot like the stuff you're used to, but they don't need to be replanted and go year round. Stacking things by height will fit more into the space; tall stuff at the north side, short herbs and greens to the south. My main
garden bed is 4x8 and I get a one or two daily salads for two, plus apples, and several servings a week of veggies from it. Grow the stuff you love in it. Two great resources for really dense planting are John Jeavons'
How to Grow More Vegetables and Mel Bartholomew's
Square Foot Gardening. Another key is to get your soil in the best possible shape so food will just come pumping out of it. Those
books (oh, and, incidentally, my own) tell how to do that.