Do you mean Solanum nigrum? The were introduced to Australia as a food plant a long time ago and used to make jams and to fill pies. Sometimes called Black nightshade.

Here is a link that might be useful: {{gwi:2116209}}

g'day fluff,

you need to make sure of i/d of plant but if it is the ones i am thinking of we call them black currants, they get used for jams a lot can be eaten off the bush but i was warned to make sure they are fully ripe. relatives of the nightshade family range from seriously toxic to edible. they come under the weed catagory but i have never seen them in complete control i let them grow around my gardens as they where a good host plant for all bugs good and bad. and tha bad bugs seemed to preffer them to our plants.

len

Here is a link that might be useful: lens garden page

I checked some of the photos here:
http://www.erowid.org/herbs/show_image.php?i=nightshade/solanum_nigrum_fruit2.jpg

I don't think that is them. The seeds are glossy. The leaves aren't hairy. It doesn't look like a tomato plant at all.

It does sound like S. nigrum to me too and we call them deadly nightshade (an innacurate name for them but a common name down here)...they do taste a little tart and should only be eaten when fully ripe ...my garden was innundated with them last year and I found them good eating in small doses...good shade plant to lessen evaporation too...easy to stamp down when they get too overpowering for some of the lesser plants
cheers
Peter

It sounds like Solanum nigrum to me too. Here is a link (hopefully it'll work...) to a more typical form of that plant.
BTW, Peter, when I went to the Salamanca Markets in Hobart in early March, the Hmong growers were selling bunches of very healthy-looking Solanum nigrum. These, I was told, were used in soups or as a vegetable by the Asian and the African cooks.
Rose-Marie

Here is a link that might be useful: {{gwi:2116210}}

They're coming up again. I had another look and those flowers are identical, with the yellow centre and five white petals. The leaves are very dark green and most have a teardrop shape with a smooth edge, though some of the younger ones have a bit of a jagged edge a bit like in the photo. That's probably the right species.

If eating a lot is dangerous then does that mean I shouldn't eat any at all?

I've decided they are safe to eat. I might try eating the leaves too:

http://www.pfaf.org/database/plants.php?Solanum+nigrum

non-native:
http://www.hear.org/pier/species/solanum_nigrum.htm

I checked a photo of deadly nightshade and it is defnitely not that. This link lists it as the only lookalike species:

http://www.ann.com.au/herbs/Monographs/solanum.htm

This may explain why some of the photos look different:

http://www.jstor.org/view/00029122/di001786/00p03306/0

If the fruits have a mirror-like gloss it is more likely to be S. americanum than S. nigrum, which has more of a satiny black fruit. But I suspect the nightshades of this group (there are several others e.g. S. chenopodioides, S. opacum) are all rather similar in their edibility/toxicity.

I think you are right.

http://en.wikipedia.org/wiki/Solanum_americanum

http://farrer.csu.edu.au/ASGAP/APOL34/jun04-5.html

http://www.bookrags.com/wiki/Solanum_americanum

(claims fruit is poisonous, and that it groes to 1 to 1.5m)