Trying to Identify an Unknown Plant

One plant in my garden is a mystery to me: I don't remember seeing it before. I don't remember planting it - unless it was one of the native plants I planted a few years ago - then forgot! It has little blue nobs in mid-summer, but otherwise doesn't have flowers. There are no plants like it in my yard. Neither Mary nor my plant-expert neighbor, Rob, recognize it.

Mary suggested I do a google image search to try to find out what it is.

I put a piece of white plastic behind the plant, to get a clearer image...

One "answer" suggested a plant found in New Zealand...

Later, I tried again, adding the words Ontario plant - and came up with a locally grown one that might be correct. It's called a Virginia spiderwort. 

Next spring I'll keep my eyes on it to see if it develops blue flowers with three petals.

For now, I have no definitive answer - but I'm glad Mary told me about using Google image search.