A squash plant grew out of some compost in with the tomatoes. I decided to leave it, and it has revealed itself finally! I'm not terribly surprised it's a butternut plant; last year's garden had several of the same mystery squash! I haven't planted any butternut squash in three years so I doubt I will even save seeds this year. Likely I will just get another mystery one or two next year!
Two of my other mystery plants were watermelon, though they have no fruit on them yet, so I doubt we will see any as it's already almost August. Can you spy one of my garden helpers below?