[en] There were 300 GeV protons used to produce Λ⁰ and anti Λ⁰ hyperons and K/sub s/⁰ mesons from beryllium, copper, and lead targets in the Fermilab neutral hyperon beam. The Lorentz invariant inclusive cross sections (Ed³sigma/dp vector³) in the projectile fragmentation region, 0.2 < x < 1.0, 0 < p/sub T/ < 2 GeV/c, are presented as functions of x = p/sub L/*/p/sub max/*, p/sub T/ and target. The neutral strange particles were detected by a conventional magnetic spectrometer and the data sample consisted of 1.1 x 10⁶ Λ⁰ s, 9.4 x 10⁴ K/sub s/⁰ s, and 1.7 x 10⁴ anti Λ⁰ s. The target dependence of the invariant cross section was found to be consistent with a power law which was used to perform an extrapolation to A = 1. Significant differences were observed in the x distributions for the three targets. The data were fit to a function of x and p/sub T/ to facilitate comparison with other experiments. Fits were also performed to a phenomenological function predicted by the triple Regge model. The model calculation was found to be consistent with the lambda production data in the region of phase space where the calculation is expected to be valid