  Within the Landau paradigm, phases of matter are distinguished by spontaneous
symmetry breaking. Implicit here is the assumption that a completely symmetric
state exists: a paramagnet. At zero temperature such quantum featureless
insulators may be forbidden, triggering either conventional order or
topological order with fractionalized excitations. Such is the case for
interacting particles when the particle number per unit cell, f, is not an
integer. But, can lattice symmetries forbid featureless insulators even at
integer f? An especially relevant case is the honeycomb (graphene) lattice ---
where free spinless fermions at f=1 (the two sites per unit cell mean f=1 is
half filling per site) are always metallic. Here we present wave functions for
bosons, and a related spin-singlet wave function for spinful electrons, on the
f=1 honeycomb, and demonstrate via quantum to classical mappings that they do
form featureless Mott insulators. The construction generalizes to symmorphic
lattices at integer f in any dimension. Our results explicitly demonstrate that
in this case, despite the absence of a non-interacting insulator at the same
filling, lack of order at zero temperature does not imply fractionalization.
