The longer fruit looks like what we in the UK call a marrow - it's basically what you get if you let a zucchini grow to full size instead of harvesting when it's immature.

The first looks like a Ronde de Nice courgette - see the link.

Here is a link that might be useful:

Thanks marrowman, but I haven't yet grown unusual or exotic squash... yet. Both veggies started out with a pronounced lightbulb shape, and thickened from the blossom end til the stem end was as thick and the shape became oval. From what I remember from growing courgette, it was green when it was much smaller, and these didn't turn green until they were quite large. The flowers seem much larger than I remember, too.

Could I have a watermelon patch? Is this how spaghetti squash grow? I think those 2 are my most likely candidates, unless there's a Jack planting a magic Beanstalk.

thanks for any insight - the vine is quite productive. =^,,^=

Not a spaghetti squash - they are usually an unpatterned banana-yellow colour.

The lightbulb shape of the early fruit is unusual. Rond de Nice is round at all stages, and courgettes/zucchini tend to grow as a fairly even sausage shape. (you're right, they are quite dark when young, but several patterned varieties get much lighter as they grow in size).

All the Curcubita family do hybridize with each other very readily though, so you could well be seeing a cross.

(I saved seed from one of my marrows a few years back, and some cross-pollination must have take place because the plants grown from them bore what looked like skinny undernourished little courgettes covered in spines - almost like little cacti!)

Aaaaaahhh! This is a dead ringer for a summer squash I planted several years ago. Can't recall where I ordered the seeds from - may've been Burpee's - but it was called simply "Gourmet".

I urge you to yank it up now while you still have a chance, because if you don't it will run rampant over your entire garden. I'm not making this up! I also had a measly two plants, and each eventually spread to nearly 8' in diameter and reached almost 5' (yes, I said five feet) high.

Once they got going they produced fruit as if there was no tomorrow. I had giant squashes stacked like firewood waiting to be chopped up for the compost pile. Never, never have I seen anything grow like these monsters! The following spring I had oodles of volunteers and I honestly couldn't rip them out of the ground quick enough.

Had they been even a little bit tasty it would've been a different story, perhaps, but they weren't - very blah. Oh, and mine were seemingly immune to vine borers (or maybe the bugs were just overwhelmed by them).

Did some Google searching today, and there is a variety of Lebanese courgette/zucchini called variously 'Clarita', 'Magda' or 'Clarinette' which has a very similar patterning to the mystery fruit, and also starts out growing lightbulb shaped.

See the pictute in the link.

Here is a link that might be useful: {{gwi:854052}}

I'll be starting a college fund for this plant - it's growing faster than a 14 year old. The larger squash are topping 10 lbs (maturing to dark green) with a hard rind. If it didn't have faint ridges I'd swear it was a watermelon. However... the young ones look just like Magda. On various sites, Magda lists a bush, and mine definately has 10-15' vines. I'll saute some this weekend and report back.

The mystery remains... I had dozens of these come up in the compost - and clueless where the seeds came from. The worm bin got remnants of spaghetti, daelicata and acorn squash, cantelopes/sweet melons of various types, maybe some cucumber bits...

Thanks for the detective work, now where's my fork... =^,,^=

My Gourmet didn't turn dark green. Maybe yours is only a first cousin... ;-)

When I saw the pictures I also immediately thought of Lebanese squash and Ronde de Nice, both very nice eaten young.

Unless you were growing ornamental squashes last year, there is no caution eating them and hopefully enjoying them. Nice freebie. However some ornamental squashes are bitter and that bitterness could possibly have transferred to this year's squashes if they are descendents of a cross. Try the first fruit with a little caution. Bitter squash tastes horrible, but a small taste will not harm you. Most likely they taste perfectly fine.

It is unlikely that they are watermelons looking at your pictures, the foliage is all wrong and the flower size. Slightly more likely that the top one could possibly be a descendant of spaghetti squash.

Last year I grew a small spaghetti squash from Parks seeds. I have volunteers this year that are the giant watermelon size zucchini squash you show as well as some white spaghetti squash.

I appreciate everyone's feedback, and here's what I think I've got (other than a wellspring of humorous chuckles from SO).

'Big green' appears to be a different plant than 'big white'. The leaves are deeply notched in comparison, and the rind is very hard, even when small.

'Big white', I thought, might be a volunteer from a farmer's market reject, so I picked up a couple likely candidates and sliced all open to compare.

The known zuc was sweet and thin skinned - so thin you could easily scratch it. Big green's skin was always dense, even when small, and the seed pattern was much larger. Big white's skin was also thicker, and a small one had a very raw, underripe taste. However, the seed pattern looks like the zuc, and it did taste zuc-like.

Interestingly, Big green's skin is turning yellow in the sun. hmmm....

So I think I have a feral zuc - that will end up stacked like firewood - and some sort of squash tbd.

To further my study, I bought 'Moon and stars' watermelon plant and a spaghetti squash plant. The watermelon looks like a watermelon, even when it's pea-sized. The SS hasn't set fruit yet, but the leaves are the closest in shape.

I've posted pix of the sliced vegs - insight welcome!

Here is a link that might be useful: veggie pix

What was the final determination of the plant‘s identity?