Glue the wooden circle to the wooden cylinder, with the circle centered on the base. Allow the glue to dry. Consult the glue instructions for exact drying time.
Measure the base of the chair (circumference and height) and cut a matching piece of batting. Coat the base with wood glue and press the batting to the base. Allow the glue to dry before handling again.
Cut an 18-inch diameter circle from the batting. Continue cutting circles, decreasing the diameter 1 inch at a time until you reach a 12-inch diameter. You should have a total of seven circles. Stack the batting circles from largest to smallest and glue them onto the seat of the chair.
Lay out your red fabric on a table. Measure and cut a 28-inch diameter circle. Lay out the cream fabric and cut out several circles of various sizes to serve as the spots for the mushroom. Sew the spots onto the red fabric.
Lay the red fabric on top of the batting and chair seat. Alternating sides, pull the fabric taut over the seat until the edge is flush with the base. Staple the fabric to the bottom of the seat. Trim any excess fabric.
Remeasure the height and circumference of the base now that it has the batting glued onto it. Add one inch to the circumference and two inches to the height. Use the measurements to cut a piece from the cream-colored fabric.
Sew the short ends of the cream-colored fabric together with the right sides facing. Turn it right-side out and slide it onto the base of the chair. Fold the top edge of the cream fabric under for a clean edge. Hand sew the cream fabric to the red fabric covering the seat, or staple it to the base.
Turn the chair upside down. Fold the extra cream fabric over the edge of the base. Staple the fabric to the inside of the base to finish your mushroom chair.