It sounds like you may have two different type of plants growing. Right now I wouldn't worry what's growing in the mystery row. I'd just wait and see. Either way you should get something yummy to eat.

I threw some spinach into my compost bin that had bolted. I am wondering if I will get random spinach plants growing in my garden next year. Good thing I really like spinach.

Cucumbers are really tiny compared to squash. The leaves are maybe 6 - 8" wide and the flowers are less than an inch across. Squash are much larger than that. Squash flowers are at least 4" across, there is no confusing the two types of plants. Squash can cross with other squash and cucumbers can cross with other cucumbers but a cucumber and a squash cannot cross.

Its always fun finding out what the volunteer cucurbits are each year.

Judging by the leaves, I seem to have volunteer watermelon.

Thanks for the info. I think it will be fun to see what ends up developing from the mystery plants, no matter what they are (my mom was hoping for cantaloupe but I really don't think so). Luckily for me, my kids love both squash and cukes so either will be welcome around here!

I have a friend that is growing potatoes in her compost heap this year, so I guess spinach is possible :).