  We present the mean-field phase diagram of electrons in a kagome flat band
with repulsive interactions. In addition to flat-band ferromagnetism, the
Hartree-Fock analysis yields cascades of unconventional magnetic orders driven
by onsite repulsion as filling changes. These include a series of
antiferromagnetic (AFM) spin-charge stripe orders, as well as an evolution from
$120^\circ$AFM to intriguing noncoplanar spin orders with tetrahedral
structures. We also map out the phase diagram under extended repulsion at half
and empty fillings of the flat band. To examine the possibilities beyond the
mean-field level, we conduct a projective symmetry group analysis and identify
the feasible $\mathbb Z_2$ spin liquids and the magnetic orders derivable from
them. The theoretical phase diagrams are compared with recent experiments on
FeSn and FeGe, enabling a determination of the most likely magnetic
instabilities in these and similar flat-band kagome materials.
