Answer: In a that small an area you could probably grow one big healthy tomato plant to the northwest where you will prepare the soil to be very rich and where you will water a bit extra.
Plant basil and perhaps chives and parsley to the east of that, along with a pepper plant if you would like one of those. These all appreciate the same type of soil and watering.
Lavender requires full sun, soil of only average fertility, a neutral pH, and must have good drainage to survive the winter, so you might want to grow it on a bit of a raised area or mound on the southern edge of the bed. This trick will improve the drainage there slightly. Along with it you could plant assorted thymes and possibly a golden or purple sage, as these plants appreciate the same conditions. They are also aromatic.
Rosemary can be grown successfully in a container (as can many herbs) and you might consider that since it is not winter hardy in your area.
Radishes and lettuce could be planted in small clumps between the larger plants. These are early season growers and will be "over" by the time the tomato grows large.
With a little experimentation you will see what works best for you.
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