Linsco, I had a similar experience with school milk, it had been warmed up because the weather was cold, and something came up my straw and wriggled in my mouth! I screamed and spat it out, whatever it was was about an inch long. I haven`t touched milk since, and that was around 1950.
My favourite school dinner, the only decent one, was meat and potato pie with shredded beetroot, lovely. The salads always had greenfly crawling all over them, and the stewed apricots we called stewed ants, because there were always loads floating on the top! This was in the late 50s though, not the 60s, I left school in 1959.