Unless specifically authorized by legislation, matching funds/cost-share for federal grants must come from NON-federal sources (private donations, state and local funds, foundation/corporate grants, and the like).
Be sure to check the origin of the funding before committing them to a federal grant project—especially if your organization receives grants from your state or local government(s). A great deal of state, city and county grants are pass-through funds from the federal government. Those funds are NOT eligible to be used as match. Federal funds that pass through a state, city, county or any other pass-through entity are still considered federal in nature.
Using unallowable match can expose your organization to a repayment of federal grant funds or a reduction in future annual award amounts.