This is some weed growing in my backyard - Euphorbia lathyris. It is a biennial which during the first year grows a fairly decorative stem with lanceolate blue-green leaves arranged in a strict opposite fashion.
I noticed the small flowers which appear in the second year are actually pretty interesting, once you look at them a bit closer.
This is where some extension tubes come in - it looks really pretty when you get really close!
These "pearls" are the pollen grains.
The plant is poisonous, and said to repel moles and other rodents that are after ornamentals or fruits in your back yard. I can confirm that.