|My son's friend has a small plant about 6|
|I think the plant your son's friend has is Mimosa pudica, a tropical plant grown as a houseplant and started from seed. Here is a photo and description to make sure.
You will probably need to order seeds or a plant from a specialty catalog as this is a fairly unusual plant. You might find it at Stokes Seeds
for example, or possibly thorugh Thompson and Morgan
Enjoy your sensitive plants!