Not sure about #1 (but it does look "weedy")
#2 and #4 are different Erigeron species (common name "fleabane")
#3 is false strawberry (Potentilla indica)
#5 may be Lactuca sp (wild lettuce, bitter-tasting)
I don't think any of them are toxic but they're not what I would consider edible either.
Thank you for helping me to identify some of the plants. I guess I should get rid of all of them, except maybe for the false strawberry, which I assume, will give an edible fruit similar to strawberry.
No it will not, as long as i know.
This may be called false strawberry in common English, but in Romanian it's called "weed"... :)
I think it refers to the look and the fact that it multiplies by stolons like strawberries do, and in no time you find it growing miles away from the mother-plant. And they have deep roots, hard to get rid of.
And not... to the fruit.
Keeping it, is entirely up to you... but be warned!
#4 looks like the fleabane I have, Philadelphia Fleabane (Erigeron philadelphicus). It is native to both the U.S. and Canada. I like their tiny white/pink flowers. Here is more info on it: http://davesgarden.com/guides/pf/go/55590/
Don't know if this would be something you would want to try but I was told that Rotenone still a chemical is a lesser of 2 evils it kills the buts by deoxydizing the insect and in turn killing it that way but it isn't as toxic as most insect killers for vegetables.
We were told this when we were on vacation up north in our state when the DNR was doing a fish count they use this in the water to kill the fish so that they could count them seems silly I know but that is what we were told. They said it deoxydizes the water and kills the fish and in turn you can use the powder on your veggie plants to kill the insects without using chemicals like seven or like chemicals. But still you would wash your vegetables of course.