Wow thanks for the clarification, nice! Yellow flowered spatulata.
Regarding collection, when I wasn't sure yet before, what I did was collect the dried buds and put in a small plastic container and shake, that will make the seeds come out
Now because I have some in the garden, if I am finished with my chores watering, and see a but ripe, I cut off the bud, squeeze like alcran said with my fingers and out comes the seeds, I just dust them off into some medium.
Don't worry too much, you have a lot of window, but don't collect too soon though.
TTFN
Arvin