This is a picture of the same garden bed. I have moved about a dozen seedlings and re-planted them in other gardens
Shown below are some of the transplanted lettuce. Yes there are some weeds in the garden too.
At some point I realised that I enough lettuce and cut the seed heads and experimented with dropping the seed heads in different garden beds.
I dropped a red lettuce seed head in the garden shown below.
I also dropped some green lettuce seed heads in bare patches in my main ornamental garden. There have be lots of seed sprout.
It was an interesting experiment. Next time I try this I will break up the seed heads more so that I don't have so many lettuce seedlings come up in the same spot.