The Lattice Strong Dynamics (LSD) collaboration has been studying SU(3) Yang-Mills with eight light flavors of Dirac fermions. This theory has accumulating numerical evidence for near conformal dynamics and a light composite isosinglet scalar meson. It could serve as a prototype of a composite Higgs sector if a reliable low-energy Effective Field Theory (EFT) could be identified. Several candidate EFTs have been proposed. I will summarize our efforts to constrain these EFTs using computed observables, including pion and scalar masses, decay constants and scattering lengths.