While you were poking around in some abandoned, ruined place that others of your people avoid, you comes across a hidden cache of ancient treasures, start with maximum starting gold for your class. (work with your DM to determine details)
Pickpocket: During your adolescence your family fell on hard times forcing you to turn to petty theft and other criminal activities involving you with criminal organisations.
The character is adopted into a Wealthy family. If he is an orphan, it is a true adoption. If he has living parents, he is treated just like a son. (work with your DM to determine details)