Blanket flower, correopsis, many varieties of salvia, and poppy comes to my mind right away. I'm sure if I wasn't tired I could come up with more.

Hollyhocks and amaranth are two big ones.

Also Nigella/Love in a mist.

It is funny you say cosmos is one of those. I know my Mum's always reseeded themselves, but I have had almost no luck getting them to grow. I think I must be burying them too much, if they like neglect they probably prefer to be on the surface.

Black-eyed susans are my number one favorite grow themselves all over the place plant. I bought my Mum's house 3 years ago, and about 12 years before that I gave her 3 black-eyed susans, which were some of the many offspring of a tag-along volunteer I got with a raspberry bush 19 years ago. There are now hundreds of black-eyed susans, all within about 100 feet of the house, and I was flinging the seeds further around the yard this fall. Any kind of plain white/yellow daisy spreads itself pretty well, too.

I have also been informed that Sweet Annie is so vigorous as a grow it yourself that someone has advised me to rip them out when I asked about the seeds.

Marcia, also a lazy gardener

Thanks everyone for your suggestions.

Marcia,
If you just toss the cosmos seeds on the soil surface, they will come up. I tried this when I first started gardening around 12 years ago and they sprouted up with no problem. Zinnias are the same way. Anyway, I know what you mean about black-eyed Susans. I love this plant!

You can also sow cleome, dill, cilantro, chamomile, angelica, blackberry lily, and verbena bonairiansis. I have also had success with columbine. These are all heavy seeders and will come up on their own. Most are easy to weed out if they end up where you don't want them.

Ellen

I've found certain vegetable greens if allowed to set seed, will self sow themselves for a fall crop and that second growth will set seed for next spring. It's just a simple matter of moving the volunteers into their own area and composting the rest. It seems every fall I mis a few nasturium seed and get volunteers. I leave them growing where they will. Even lazier than hand scattering.

I was sure happy to read this message. I can't wait to try this. Does anyone know if daturas will grow this way?

ibartoo,
I 've been told by a master gardener here that her night flowering datura (white) self sows in a gravel bed each year.
I've been told here on GW that teh other types of datura don't self sow that easily.

bellarosa-
Another plant that self sows is linaria. Some of my collected seed blew out of the garage and then bloomed there in the gravel- as a little surprise to me!

A neighbor here lets the sweet peas fall from the vine and never replants them.

anthemis (kelwayi) also called chamomile- self seeds and blooms the same season for a second flush of blooms, as does salvia 'transyanica' and california poppy.

morning glories and catmint, do this to a fault- Aaargh!

You'd be surprised how many seeds on the list by Thompson and Morgan say "surface sow"
karen

I would like to add Larkspur, Lychnis coronaria, Euphorbia marginata, Centaurea cyanus, Echinacea purpurea to your list. I flung the seeds everywhere in my garden and let them grow at will.

Marcia, the plain white/yellow daisy must be Feverfew. I love that one too. I have at least 4 forms of them and scatter the seeds everywhere in the garden. If there are too many of them, I just pull them out.

I love larkspur, but can never grow it. Pitimpinai, when is a good time to sow it? I love the deep blues the most. Anyway, I can't wait to try the seeds everyone has suggested. Thank you everyone!

My Balsam self sows too and sometimes my tomato plants "volunteer" as do borage!