(or what are known as weeds by tossers)

I have no favourate, but a much overlooked one is

Dandelion

The case for
1) Huge show of yellow when there arn't many other plants (can form great swarths)
2) is benign
3) is edible (all of it, roots, leaves, flowers)
4) helps the bumble bees when they wake up, early source of food
5) smell one on a sunny day, get your nose into the flower and breath in......It smells of honey
6) has play value for children and adults (dandelion clocks)
7) has play value by using the stalk milk to make tiny brown rings all over your skin (when it dries) I used to do this loads, like what people use henna for
8) watching the parachutes can be entertaining for those that are zonked