Input needed

The deck of our rental house has a little planting box all the way around it.
It's about 3 inches wide, and 3 inches deep.
My dad used to use to plant flowers in the box during the spring and summer, but I'm trying to wrack (rack?) my brain for a type of edible that I could plant here instead.  I thought about herbs, but I could never use THAT many herbs.  Plus, the herbs I truly love (basil, parsley, and dill) grow freakishly tall.

The entire deck is southwest facing and during the summer it gets direct sun from 7 am - 8 pm, i.e., lettuce would not do well here.  It also faces the road, so it would need to be somewhat not ugly.

So, any ideas?