I have a volunteer squash this year, growing next to a tomato plant. It flowers early in the morning, and by afternoon the flowers are dying.
I don't know what variety it is, since I didn't plant it, but I suspect it is a pumpkin from when I made jack-o-lanterns last fall. The seed must have fallen there and sprouted this year.
I've had mixed luck with various squashes throughout the years, some years I'll get some good ones, but other years the flowers never form into a squash. If you have any idea why this would happen, leave a comment.
There are a bunch more flower buds so I know there are more blossoms coming.
All photos taken by me, I hope you enjoyed looking at them.