to All Things Plants!
I agree with HamiltonSquare, slice one down the middle and see what you find. Post another photo of both the whole seed and the one sliced in two pieces. Alos, a photo might show up with a bit more clarity if they are laid on a white background like a paper towel.
Also, can you tell us the part of the country/world where you found the seeds? You don't have to be exact, some folks don't like listing their exact city where they live but you could say for instance, East Central N.Y., Southern Florida, Northern Virginia, etc. That would at least narrow down what types of plants grow in the area and could possibly help with an exact ID as to what plant the seeds came from.