I'm going to get a present that looks like marijuana for my moms birthday
Is this something you find funny?
the truth is too boring
You shouldn't try to trick your mom like that, unless it's a joke that you both can enjoy.  You should try to choose a present that she will appreciate, rather than one that only amuses you.
It's going to be a surprise.
This is a mean thing to do. Why can't you surprise her with a gift she will actually enjoy?