Beginner Gardening: What is this Please!, 1 by Craggy

Craggy wrote:
I have recently started useing a greenhouse and have planted a Vine in some open earth at the rear, while I was seeding up some peppers and chillies, I assume that one of the seeds has landed in the earth as a shoot appeared, I decided to leave this and see what turned up.
It grew and grew, and when I returned back prom a two week holiday I was shocked to see the size it had grown. Please see image, could you please let me know what it is? and what part is edible? and which is the seed for the future? The part that confuses me is the large prickly growth that is between each stem.