Tansy-does it self seed?

I have a couple of tansy plants which flowered earlier. The flower heads are now dried up on the plant and I noticed that when I acidentally rocked the plant something (possibly seeds?) came out of the flower heads. Is it just a matter of shaking the plants then forking over lightly to get new plants next year or are these not seeds? thanks

 

Hi L-G usually tansy is grown from seed in spring or by root division it can be invasive in some parts of america its outlawed it can be used as an insect repellent usually planted outside doors to keep ants out,why not save a few seeds in case the ones you fork in don't come up then plant them next spring

 

didnt know all that! thanks