Smokerbill
Free Ranging
I don't know if my fingers have the dexterity. The seeds are a little smaller than radish seeds, and very slick. I guess I could gently roll them between a couple sheets of sandpaper.Many plants have a tough seed coat to withstand a digestive track. Try nicking the seed coat so moisture can get it. They may be old but might surprise you. Weed seeds can stay viable for a long time.