A few years ago, when I first moved into my house, my mom and I went to the local garden tour. As a bonus, they gave out free plants. I was pretty sure I planted mine in the way back/alley garden, but I couldn't for the life of me remember what it was.
It has been growing a little bit each year, but I wasn't sure if it was a weed or a real plant. Surprise! It's a lilac. It finally bloomed!