marigolds, green beans, - check back of seed packet and it will tell you how many days to gernintation
In my school the kindergarten has done green beans successfully. We put them into a plastic sandwich bags with a very wet paper towel. Each student has their own with their name on it. Then we tape them where they get plenty of sunlight and water as needed. This way they get to see the seeds sprout and the roots grow. They do daily observations that they draw and write into a journal. It doesn't take long and there will be a stalk growing out the top of the bag.
I agree - grass seed is my favorite. You can put it in a knee high panty hose with potting soil and cedar shavings. Tie the open end into a knot. Then in the middle of one side pull out a piece and tie with a rubber band to make a big nose. Glue on wiggly eyes. Set it (knot side down) in a paper bowl. Water it daily and it will begin to grow hair in days....my kids LOVE LOVE LOVE it. In fact, we are doing it tomorrow