Herodotus (link to Google Books) - trans. Rev. William Beloe 1831. P.236: The neck of land which stretches from the country of the Gindanes towards the sea is possessed by the Lotophagi who live entirely upon the fruit of the lotos
The Fragments of Empedocles(link to Questia.com) trans. W.E. Leonard Ph.D., Chicago, 1908. Part 2 says much about transmigration of souls and the Orphic/Pythagorean traditions.
Plato's Republic(link to archive.org) trans. Lewis Campbell M.A., LL.D., London, 1902. In Books II & III Plato (428-347 BC) develops the dietary ideas of Pythagoras.
The Lives and Opinions of Eminent Philosophers(link to Google Books) by Diogenes Laertius (?412-?323 BC), trans. C. D. Yonge B.A., London, 1853. Includes a section on Pythagoras, animals as food etc.
Ovid's Metamorphoses(link to archive.org) By Publius Ovidius Naso (43 BC - AD 17). This edition pub. London 1822. Book 15, p.516 is a biography of Pythagoras. p.519: 'He first forbid animal food to be served up at the tables of men'.
Seneca's Morals(link to archive.org) - by Lucius Annaeus Seneca (c.5 BC - AD 65) - trans Sir Roger L'Estrange, New York, c.1870. "I gave over eating of flesh", p110
Plutarch's Morals Vol.5(link to archive.org) by Plutarch (c.AD 46-c.120)- edited by W. W. Goodwin Ph.D, Harvard, 1878. Includes the essay 'Of Eating Flesh'
