I think it all depends on your type of weather, what are your limits and things as such, but here is a website that might help you a little? I used this when I was volunteering at this child care place. I got at least one idea on there. http://funadvice.com/r/14uaigjb7t0 Hope it helps.
aloe vera is easy to plant and will surely grow with much taking care. Rose is strong but a little attention. or http://funadvice.com/r/bhfb17cimha I am not sure which you can find there in USA,,,lol
When I was in 1st grade, my teacher gave me marigolds to take home and transplant - it worked! :)
I would say any kind of cactus is. They generally don't need a whole lot of care.
pansies are really easy to take care of