Hey everyone

I am a big fan of Towerdefence games, so I thought about
writing one on my own(no, there are never enough games

)
The problem is, I am completely untalented in graphics.
So I thought, I could just ask here, if someone has some
free-to-use tower Defence graphics.
The map consists of tiles with 20*20pixel, so enemies, towers should have a maximum size of 20*20.
The environment tiles may be bigger since the can be cut in pieces

Since this project is for learning purpose only, and friends are forced to play it, I don't want
someone to create something new and only want sprite, you already have.
If no one here got something, I'll google and ask the people for their graphics,
or.....create my own(I tried, really, but the best cases I would get done are smileys(maybe)*g*)
Thank you much,
Aestond