Mysterious Plant

I have planted lots of seeds of a mysterious plant. I thought, it was a pumpkin seeds. At least I was told they were pumpkin seeds. But the fruits are not orange nor yellow. They are green. Dark green. And the taste of the fruit is very similar to zucchini, but I think better. The fruit is more soft and delicate. Good for salads and also for hot dishes. And it grows round and big :)