I harvested my first lettuce seed (ever) a couple of weeks ago. It looks like you still have to wait awhile. After the yellow flowers open, they will eventually form what looks like miniature white dandilion puffs, then the seed pods will start to turn brown. That is when I collected mine. I snipped off all the browning seed pods. Just last week I opened up a few and planted a new batch of lettuce, which is starting to germinate. Like I said, that was my first time, so I don't know that it was right, but it worked... I am getting baby lettuce! Best of luck to you.

Teresa has it right. When you pick the browning or opening dandelion-like seed heads, let them set out to dry before storing the seeds so you don't trap moisture in the container and get mold.

Yes. bring some seeds in for safe-keeping, but also throw the seedheads on the ground where you want lettuce to grow next year. Some may come up! Right now all my turnips, arugula, and mizuna came from seeds shed this spring. Didn't plant a one of them, and they look great.

Here is a link that might be useful: compost gardening

Thanks for ALL the help!

Am looking forward to them flowering.

I saved my first this year also and found I tried too early. The looked dry enough but put out a sticky, milky substance. I let dry longer and the were much easier to harvest without all the stickiness.

Nice pic = )

Here's what I did - I cut the entire stalk, once all green was gone & the fluff had formed, the placed it in a large paper sack & hung it to dry. Once dry, I rubbed the seedheads between my hands to separate seeds from fluff & gently blew away the chaff (did this outside) - I got a LOT of seeds = )