In Lev. 19:19 and in Deut. 22:11 Torah talks about suitible tread to make clothing from. Deut says not to mix wool and cotton together and Lev says not to put two sorts of thread together. My question is for today, can we then mix polyester and cotton, cotton and spandex, ect together? or are these also forbidden. If we can wear these new kinds of mixes, how does it apply to Lev.

The Talmud in Yevamot 4b explains that the verse in Leviticus 19:19 is also talking about the restriction of wearing wool and linen. All other material combinations are permitted. The Shulchan Aruch (Yoreh Deah 298:1) is very specific: "The only threads that are prohibited are threads of sheep wool with linen."