Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
prae-sterno, ĕre, v. a., to strew or spread beforehand, to prepare (mostly anteand post-class.): eo praesternebant folia farferi (al. prosternebant), Plaut. Poen. 2, 32: altaria, to prepare, Stat. S. 3, 2, 114: jubet serta et elysios animae praesternere flores, id. ib. 5, 2, 257.
Pass. fig.: tuis laudibus tuisque virtutibus materiam campumque praesterni, Plin. Pan. 31, 1: illud peto, praesternas, etc. (al. less correctly, praestruas), Plin. Ep. 5, 8, 14.