DS has done two fab ones in kindergarten last year and the year before.
Last year they took egg shells and cracked just the top bit off -- not in half, a bit less than half. Filled the empty egg shell it with soil and put some cress seeds in it. Glued two googly eyes on and drew a mouth on with marker. Then used the hot glue gun and glued it to a foam base (could use thick paper) shaped like two feet. It only took a day or two for the cress to grow and it was little hair sticking out! Soooo cute. I have a picture on my phone so will edit this post in a minute to add it.
The other one was a blown out egg (pin hole in each end, blow the egg out.). If brown paint egg white. If white, leave it as it is. Glue a white feather to the top, a tiny square of orange paper folded into a triangle on becomes a beak, and again glue to some paper to make feet. Black sharpie makes eye and it's a wee chick! I know I still have this one but can not find a picture of it..... I will try tomorrow because I am sure the egg is in DS's bedroom and he is asleep.
Both are just so easy and simple and look sooo cute - and def look like the kids have done them but still look awesome, yk?