Extra pay for working during weekends is generally a matter of agreement between the employer and the employee (or the employee's representative). The Fair Labor Standards Act (FLSA) does not require extra pay for weekend work. However, covered, non-exempt employees must be paid at least one and one-half times their regular rates of pay for for the time worked over 40 hours in a workweek.
DOL Web Pages on This Topic
"Is Extra Pay Required for Weekend or Night Work?"
Information about work hours from the elaws FLSA Advisor.
Coverage Under the Fair Labor Standards Act (FLSA) Fact Sheet
General information about who is covered by the FLSA.