Garden mysteries

Does anyone remember the summer?  That long hot time when the seeds we planted were growing so fast?
There were two mystery vines that sprouted from a deck planter and flourished in the heat.  One had a fruit the size of a tennis ball and the other had squash-y flowers.  But, all good things must end and I cut them off theeir vines.  I think the ball is a honeydew melon - definitely a compost volunteer  seed - and the other looks like it could have grown to be a pumpkin.  What do you think?

Then, while we were tidying up in the garden, I cut away a bunch of dead goatsbeard stalks.  Underneath I found another mystery!  There was the beginnings of what looks like a tree.  But I really don't know what it is.  The leaves smell sort of soapy.  Kind of like lemon balm but not so lemon-y.  Any ideas?

And right beside it was a lovely plant with mottled arrowhead-shaped leaves.  It looked familiar but I just couldn't think what it could be.

Then I remembered that we had bought some plants at a local plant sale and maybe this was one I'd forgotten about.  Some sleuthing in the garden of origin and it's not a mystery any more.  The beautiful leaves belong to Arum Italica.  It puts up its new leaves in the late autumn which is why I hadn't really noticed it.  That - and it was hiding under a few stalks. In the spring, when the leaves die down, it will have an orange flower.    That's a good mystery to have solved.