Those are Lilac seeds (Syringa sp.).
Good afternoon, Mark! This is Lane Wiens, the horticulture agent for Shawnee County. Earlier today, I had a client bring in a sample of seeds to identify that I'm having trouble with. I've attached a couple of pictures that will hopefully help you with identification.
In both pictures, I am using a dime as a size comparison for the seeds. The brighter of the two pictures was taken through our microscope, the second just with my phone camera.
If these pictures are not enough to identify them, I can bring a sample of these seeds with me to Manhattan for the Hort PFT meeting next week.
Thank you in advance for your help, have a good day!
Lane Wiens, M.S.
Shawnee Co. Horticulture Extension Agent
1740 SW Western Ave, Topeka, KS, 66604