This basketball-sized yellow squash in my garden looks nothing like the picture on the seed packet it's from.
—Ronna Wagner, Littleton, Colorado
There may have been a mix-up in the seeds. You might want to contact the seed company. Most of these businesses are accommodating in these situations.
There still may be another explanation. If you previously grew squash in this area or used compost to amend the soil, you may have some volunteer plants. Volunteer plants sprout from the seeds of past crops—either from squash that didn't get harvested or seeds that ended up in the compost pile after dinner.
Since different varieties of squash will cross-pollinate in the garden, their offspring may produce unique fruit showing some or no characteristics of the original varieties planted. The fruit from the volunteer offspring are edible but may be unique in color and shape.