A tree at my house in Seattle, Washington, USA has these leaves. Can someone tell me what it is?
It looks similar to a Cotinus coggygria, which is a shrub that we call a Smokebush in the UK. But given your location, it could be Cotinus obovatus, known as American smoketree.
The leaves will start green and progressively change colour to deep reds in the autumn with sprays of pink-purple flowers in the summer that from a distance look like smoke, hence the name.
Here are some images I have found on the web.
I think this may be a Chokecherry. Prunus virginiana 'Canada Red'
Found this on a Washington nursery website so it would make sense that it would be planted in your region. I am inclined to think it is closer to this species than a smoke bush based off what I can see from the flower in the photograph.