Saving Lettuce Seeds

I have to admit that I did not intend to save lettuce seeds this year, mainly because the thought just didn't occur to me.  But my late-spring planted lettuce all bolted quickly when it got too hot early this summer.  One day, my cut-and-come-again lettuce patch just started shooting up these tall flower stalks.  I left them alone because I was curious to see what would happen.

Well, the tall flower stalks (about 3-4 feet tall, I think) started putting on hundreds of these tiny flower buds that, according to the internet, each only opened for quick 30 minutes to self-pollinate and start setting seeds. I caught a few of the open flowers here and there throughout this summer, as you can see in the picture above.  The self-pollinated flowers turned into fuzzy seed heads, like dandelion, as a bunch of seeds formed inside each seed head.

I'm guessing that the fuzzy stuff is intended to carry mature seeds away by wind.  But I also noticed that many seed heads still had seeds intact and just lost the fuzzies.

So I took each seed head and crumbled it gently between my thumb and forefinger to harvest the seeds.  It was pretty easy, and I could do it while the seed head was still attached to the stem.  I then unloaded the contents pinched between my thumb and forefinger to a paper plate.  I repeated this process, um, like a hundred times until I got tired of it and decided I probably had enough lettuce seeds to plant an acre.  In case you're wondering, my vegetables garden is not an acre.  Not even close.

I'm not really sure how I can separate the seeds from chaff, as they all just came apart together.  Does anyone know of a easy way to do this?  Otherwise, I guess it won't hurt anything to just scatter-sow these seeds along with the chaff during next planting time.

Some lettuce seeds were black and some were white.  I'm assuming they are different varieties of lettuce, as I had several different varieties (that I can no longer identify from the bolted lettuce) planted in that corner of the garden. 

There are still hundreds more lettuce flowers and seed heads in the garden.  I don't know if I have the heart to just pull them all out, but I don't really want to harvest any more seeds, either.  Oh the dilemma.  At least I learned my lesson for next year.  If I decide to save lettuce seeds again, I will just let one or two flower stalks develop and that will still give me plenty of seeds, far more than what I can reasonably use or share.  When the weather gets too hot, I will pull out the remaining lettuce to make room for something new, like bush beans.