Members of the county board of education or board of trustees may serve without pay. Each member of the board may receive a per diem for attendance at board meetings and may be paid mileage to and from such meetings. No member may receive per diem and mileage unless in actual attendance upon a meeting of the board. When any member of a board is directed to travel outside the county or school district on official business of the board, he may be allowed actual expenses incurred as a result.