Right now the garden centers are bursting with vegetable plants and seeds. They might even be starting to go on sale!
The best things to plant right now are the warm season crops like cucumbers, melons, peppers, tomatoes, squash, eggplants, and herbs. I have planted these things as late as the last week of June and they were awesome in the fall! *You will have success at this time of the year with warm season vegetables if you plant plants, not seeds.
In late July and early August, we can start some fall crops (from seeds) of cool-season things like lettuce, radish, spinach and other greens.