I believe that is Mock orange, Philadelphus. Probably the non-native one if you have some fragrance.

Yep, Philadelphus coronarius or some cultivar thereof :-) This is a suckering shrub (like lilacs), so relatively easy to separate exterior young suckers/shoots to start new plants.

There was a mock orange like this planted outside my bedroom window when I was growing up.....the wonderful fragrance - strongest on a warm evening - is very evocative and triggers all sort of pleasant memories of my childhood :-)

When I got married we had no money. I bought a bunch of yellow roses in the market and pinched a load of mock orange from over someone's garden wall. Quite the classiest bouquet imaginable.

Thank you all! I am going to try to propagate it so it grows somewhere other than behind the tool shed.