  We present a lattice QCD calculation of the ground-state energy shifts of
various baryons in a medium of pions or kaons at a single value of the quark
mass corresponding to a pion mass of m_\pi~390 MeV and a kaon mass of m_K~540
MeV, and in a spatial volume V (4fm)^3. All systems are created using a
canonical formalism in which quark propagators are contracted into correlation
functions of fixed isospin/kaon density. We study four different systems,
\Sigma^+(\pi^+)^n, \Xi^0(\pi^+)^n, p(K^+)^n, and n(K^+)^n, for up to n=11
mesons. From the ground-state energy shifts we extract two- and three-body
scattering parameters, as well as linear combinations of low-energy constants
appearing in tree-level chiral perturbation theory.
