The ornamental design for buttons and placket for a garment, as shown and described.
FIG. 1 is a front view of buttons and placket for a garment showing our new design; and,
FIG. 2 is an enhanced front view of FIG. 1 of buttons and placket for a garment showing our new design.
The broken lines showing portions of the buttons and placket for a garment in the figures are for the purpose of illustrating environmental structure and form no part of the claimed design.