Does anyone know what this plant is?

its a type of euphorbia and if you like it its not a weed. it might be the caper spurge its hard to tell from the photo. but be carefull if you do decided to pull it out its cut stems ooze a latex that causes chemical burns on the skin. made worse if exposed to the sun at the same time.

Thanks Seaburngirl, I googled euphorbia and I found what it is - its called a Euphorbia lathyris - moleplant.

Thanks for your help :)

Once you've got it, you've got it! If you like it OK, if not don't let it seed. I was given one and now it is springing up everywhere. Its easy to pull out though - wearing gloves!

If is one of the few plants we yank out regularly as it grows like a weed in our garden...