I've been growing yellow courgettes. What I really like about them is they're very easy to grow. All I do is water them every 2 days and they don't seem to be affected by pests, unlike my broccoli and bok choy.
It's easy to know when to harvest the vegetables too as you can clearly see them. They also grow these unusual looking flowers. I will get a photo of the flowers for you soon so you can see.