Well there could be so many tales and reasons behind lord Ganesha and goddess Laxmi being worshipped together out of 36 crore gods and goddess in Hinduism, but this one sounds the most rational to me. Hinduism believes that each god and goddess have different importance and worshiped for a different reason so let me first talk about their individual importance in Hinduism. As wealth is the crucial element of any civilization, we have a supreme deity to be worshipped and bestow the wealth and prosperity upon the devotees, goddess Laxmi is the supreme being worshipped for affluence and riches.
The son of almighty Shiva, who drank the venom created from the churning of the ocean to save world from effects of venom and which made his throat turn blue, is one of the most worshipped god in hindu dharma. Ganesha is widely revered as the remover of obstacles, the patron of arts and sciences and the deva of intellect and wisdom. As the god of beginnings, he is honoured at the start of rituals and ceremonies. Ganesha is most commonly revered as the god of intellect.
Wealth without intellect will only result in misusing of wealth, one must first acquire the intelligence to spend the wealth in the right manner and then only one can multiply that wealth and prosper. So worshipping the patron of wealth with patron of intellect could be the best possible way of acquiring two indispensable things in life and that could be the evident reason of worshipping lord Ganesha and goddess Laxmi together.Reason Why Goddess Lakshmi and Lord Ganesha are Worshipped Together. by Acharya Dharam Shastri