My dug in compost heap has produced some freebies in my garden bed. The
tomatoes I can ID but I have something else I don't know. It came up as half
a dozen plants with two roundish leaves, sitting opposite each other.
They've developed into a lot of very large leaves with a prickly feel. I'll
assume I'm looking at zucchini, watermelon or pumpkin. Any idea on how I can
tell?

Liz