Yellow squash comes in a number of varieties including crook-neck, straight-neck, patty pan and yellow zucchini. Like all summer squash, yellow squash have an edible thin skin that does not need peeling, and are usually tender and mildly sweet. Select yellow squash that are less than eight inches long; the vegetables can become bitter the larger the plants grow. Make sure the squash are firm, particularly at the stems, and have bright skins. You can eat summer squash grilled, roasted, steamed, or raw.