We need more people on this thread.
There must be someone with more knowledge about these seeds who frequents this forum.
When you tasted a little, did it make your mouth numb? Brucine, one of the alkaloids in Strychnos nux vomica, makes your mouth numb. I don’t know what isolated brucine tastes like. It may not be as bitter as strychnine. Little is known about brucine. It’s been overshadowed by strychnine in the literature. Brucine is about 1/20 the potency of strychnine and is said not to produce convulsions. It’s supposed to decrease one’s sensitivity to sensory stimuli, which is the opposite effect from strychnine. But I’ve also read conflicting reports saying that its effects are the same as strychnine, just weaker.
To my eyes it looks related to Strychnos nux vomica. The color, the texture, some of the other features, all look like nux to me, except for the shape. Nux is flat, disk shaped, and yours are fat and rounded.
If no one knows the exact botanical identification of it, how do they know if they sold you the right seeds or not?