  We compute pseudoscalar meson masses and decay constants using staggered
quarks on lattices with three flavors of sea quarks and lattice spacings
$\approx 0.12$ fm and $\approx 0.09$ fm. We fit partially quenched results to
``staggered chiral perturbation theory'' formulae, thereby taking into account
the effects of taste-symmetry violations. Chiral logarithms are observed. From
the fits we calculate $f_\pi$ and $f_K$, extract Gasser-Leutwyler parameters of
the chiral Lagrangian, and (modulo rather large perturbative errors) find the
light and strange quark masses.
