A mower blade assembly attaches to a rotatable spindle and includes a mounting plate which defines a first pin aperture. The mounting plate and a retaining plate are attached to the rotatable spindle. The retaining plate defines a second pin aperture. A movable pin plate comprises a pin. A blade is selectively attachable to the mounting plate. The blade defines a retaining plate aperture and a third pin aperture. A biasing member urges the movable pin plate from a disengaged position to an engaged position. The pin is engageable with the pin apertures for mounting and retaining the cutting blade to the mounting plate. The blade is attached by moving the blade over the retaining plate aperture, urging the movable pin plate to the disengaged position, rotating the blade, and releasing the movable pin plate. Another embodiment includes a force finger.