I planted 2 kids of pumpkins, both Burpee, one is a “Prizewinner Hybrid” and the other 2 plants are supposed to be “Jack O Lantern”.
There’s 2 plants, both supposed to be Jack O Lantern, planted inches from each other (both were coming in so well I couldn’t bear to pull one :lol)
One is coming in like what I think a normal pumpkin should: green and round:
(The Mystery Plant)
The other came in yellow from the very start and is a little more oval:
What is this thing?
This is the “Prizewinner” for clarification, it came in green like the first picture:
Salem, OR
When I googled (because I have no idea what it is!) I came up with this picture http://web.ukonline.co.uk/suttonelms/yellow%20pumpkin.jpg but I don’t know what it is as it has no explanation with it. It looks a lot like your mystery plant though!
This http://rodrigvitzstyle.typepad.com/rodrigvitz_style/2007/07/mondays-with–4.html kind of looks like it too. Maybe you just have a yellow pumpkin growing?