Spiral.  r = 3*x.
Rose (5 leaves).  r = 60 * cos(5*x)
Rose (5 leaves).  r = 60 * sin(5*x)
Parabola.
Cosine.  y = 20*cos(1/20*x)
X cubed.  y = .001*x^3+20
Rose (16 leaves). r  = 80 * cos(8*x)
Bifolium.  r= a sin(x) cos(x)^2.
Cardioid. r = a(cos(x) - 1).
Folium of Descartes.