These are the seeds of the Irani Hogweed. Often they are called Angelica seeds, but this is a mistake. Angelica is a herb of another variety entirely.
The seeds are available from Afghani and Middle Eastern groceries, and some groceries specialising in German and European products. The whole Irani Hogweed Seed is often used in pickles. For many other uses, they are ground into a powder, Golpar Koobideh, which has an earthy, slightly bitter and sour taste. It is used in Middle Eastern and some European cooking, and goes excellently with broad beans, pomegranate, mushrooms, potatoes and brown lentils. It is also used with rice, vegetables and soups.
One of the most popular uses of this particularly Persian spice is to sprinkle golpar over baghali pokhteh, or cooked fava beans. A beautiful and popular use of the powder is to sprinkle golpar over a bowl of pomegranate kernels or a Pomegranate and Cucumber Salad. It mixes well into yoghurt, and is commonly used in lentil soup.
The powder is often mixed with salt for an intriguing seasoning called Golpar Namak, which you can see here.