I am a newbie myself, but I am learning fast from this forum. So, if you allow me ...
First, let's get the "bad" out of the way:
If you take random shots and ask for C&C, you can't expect much.
Having said that, I think that you might have a "theme" in there: weeds - since there are weeds in at least 3 of the four pictures (I can't tell much about the first one.)
One interesting possibility would be to take some pictures from the weeds' point of view (i.e. get on the ground) - possibly using a short focal length to have the weeds in focus and the background blurry.
I also think that with the light you had, you might want to edit the photos for more contrast (Picasa from Google is free and it's pretty good for adding shadows and highlights.) You might also experiment with the black-and-white filter on Picasa. I find that if the light is boring, sometimes B&W can be your best friend.
Just some advice from an only-slightly-more-experienced-newbie.
Ciao,
Alberto