My garden is at its best in the fall, due to the large amount of greens I plant. But you will have to be content with greens this year. No tomatoes, zucchini, or corn.
In june-july you can plant radicchio and broccoli. In july plant kale, peas, tatsoi, lettuce, bok choi and arugula. In August plant broccoli rabe.
In june you could consider planting carrots and beets as well. In august you could consider radishes and in september pea shoots.
You should also plant all sorts of perennial herbs in june or july. Sorrel, mint, thyme, sage, lemon balm and oregano. They will be there for you next april and forever after.