6 (6,7) buttons.

Needs 4 colors of yarn:

White-4(5,6) 20g balls
Light Blue-2(3,4) 20g balls
Light Brown-1(1,1) 20g ball
Dark Brown-1(1,1) 20 g ball (to embroider wheels and birds)

In The Knitting and Crochet Book, this pattern is shown on the cover and on page 158, with the instructions beginning on page 156.
In the First Things First booklets, it is Pattern Number 12, with instructions starting on page 11, and shown on the back cover.
In Holiday Knitting Volume 6, this is Pattern Number 21.