I just know about lamb's ear. Once the flowers are gone, pinch your fingers at the bottom of the stalk and pull up. The seed pods will come right off.

You do have to make sure the lamb's ears seeds are ripe first, though. Easy to tell. If you look down the seed "pods" (not technically pods), which would be open at the flower end, they should be black (or dark brown), else they may not be viable. I find that all you need to do (if the whole stalk has ripe seeds) is cut the stalk , have it over a sheet of newspaper, then shake them on it.

If you do a Google search for "molucella laevis seed collecting" (without the quotes), there are some good pictures in the first search result.
I'm not good at explaining things, but I'll try: When the flower (or bract, or bell) turns tan/brown and dry, there are four seeds way down in each bell. Just watch out for the two pickers by each bell on the stem of the plant!
Kelly

Ditto on the lamb's ears. You will see the openings on the side of the plant. I just whack the stem and shake it into a bag. The little black seeds tumble out.

Thank you everybody!!
Debbie

Additionally the bells of Ireland seed will appear as small brown triangles...kind of odd looking.

Ditto on the spines...ouch!