  We identify the maximally dense lattice packings of tangent-disk trimers with
fixed bond angles ($\theta = \theta_0$) and contrast them to both their
nonmaximally-dense-but-strictly-jammed lattice packings as well as the
disordered jammed states they form for a range of compression protocols. While
only $\theta_0 = 0,\ 60^\circ,\ \rm{and}\ 120^\circ$ trimers can form the
triangular lattice, maximally-dense maximally-symmetric packings for all
$\theta_0$ fall into just two categories distinguished by their bond
topologies: half-elongated-triangular for $0 < \theta_0 < 60^\circ$ and
elongated-snub-square for $60^\circ < \theta_0 < 120^\circ$. The presence of
degenerate, lower-symmetry versions of these densest packings combined with
several families of less-dense-but-strictly-jammed lattice packings act in
concert to promote jamming.
