It started out looking like a zuchinni but it was on long vines. Very prolific.

I've never seen one like that before.

If you leave zucchini to grow they can be large, there's a photo of a yellow one on this link ..

http://www.createfamilyconnect...

Did you grow zucchini?

Looks like it might be that @Jrsbugs. Squirrels must have planted it. But it was on a long vine. Are there zukes that wander all over? Thanks!

Some vines do grow very long, some are bred to be more compact. Growing conditions can make them grow longer if they get a lot of shade. Some good info ..

http://www.botgard.ucla.edu/ht...

What color are the seeds? If they are dark I would guess luffa. Which is edible when young but if left on vine to dry it becomes fibrous inside; soak and peel off skin and. It's a bath sponge.

I did plant luffas.

Luffas go directly from green to brown. I've never seen one yellow.

Could it be a Delicata? I just came from the grocery store - when I saw the Delicata I thought it looked like your mystery.