Well, there's "cheeses" a type of weed with scalloped leaves.
This weed is a fine substitute in magick for Marsh Mallow, though it won't have much root to it. It grows wild all over the place, in much of europe as well as the US. It was used as a medical substitute for marsh mallow in it's day, as well as being easier to care for and requiring less water.
Here's a nice link with more pictures and so on. Should give you enough to go on.
http://www.oardc.ohio-state.edu/weedgui ... asp?id=470
EDIT: Oops, you live in India! I'm not sure it grows there. Though you might want to try what we all "velvet leaf" which we often get in potting soil that we get imported from India. I read that it was common there. But India is a big country with as many different climates as we have here in the US. So I have NO idea if this plant is available to you. Here's a picture anyway, and see if you have seen it off-chance.
Use the flowers rather than the leaves for your purposes.
Hmm. I will have to investigate wishing plants that are available in India.
Maybe there are some cooking spices that are good for wishes! Vanilla candy seems to be the easier one to come up with, I have to agree.
Here's another link for velvet leaf.
http://davesgarden.com/guides/pf/go/792/