I like the yellow squash, I think it has more flavor (fried in butter) although you can't use it much in cooked dishes; it falls apart and gets mushy. Zucchini is great for that. I can't wait for the tomatoes either. My ENTJ just spent $2.00+ for one the other day and I just about passed out. Hard, tasteless red round thing that only looks like a tomato.
The swiss chard sounds great. My grandmother used to grow it. I loves me my spinach too. I'd love to grow romaine lettuce but it gets too hot here too fast to grow them full grown, meaning I have to pick the young leaves off for salad instead of having fully grown plants.
As for corn, the stores around here wanted $27.00lb for corn seed. I told them to forget it. I've got some old seed around here somewhere. It won't germinate as well but I'll risk it.