Our rugs are rolled, and vacuum packed for protection and may have some waves or ripples when it’s first unrolled. One technique to quickly flatten your rug is to reverse roll it. Spread the rug out and roll in the opposite direction. Tie it to keep it in place, and check after a day to see if it lays flat.
If you still see some creases and bunching in the pile, try placing the rug flat and face down, with heavy, flat objects on the affected areas. Books and clean boxes can be useful for this technique. After 2 to 3 days, waves or ripples should relax. Place heavy objects on corners that stick up until they lay flat on their own.