grid.rect(gp=gpar(col="grey"))
angle <- seq(0, 2*pi, length=10)[-10]
grid.polygon(x=0.25 + 0.15*cos(angle), y=0.5 + 0.3*sin(angle), 
             gp=gpar(fill="grey"))
grid.polygon(x=0.75 + 0.15*cos(angle), y=0.5 + 0.3*sin(angle), 
             id=rep(1:3, each=3),
             gp=gpar(fill="grey"))