These started showing up in my backyard this year, I believe they migrated over from my neighbor's yard. Are they lilacs, or are they something else? This picture was taken in mid-May in Saginaw, Michigan.
The specific flower is Dame's Rocket. Definitely a mustard, and apparently commonly confused with phlox. Also an invasive species in Michigan.
not lilacs, looks to be some sort of mustard... similar to, but not: http://www.illinoiswildflowers.info/weeds/plants/blue_mustard.htm
