Yea. Positive and negative muons and pions were found after WWII. The anti-proton wasn't discovered until 1955 following the construction of the Bevatron, an accelerator powerful enough to reach the proton/anti-proton rest mass of ~1 GeV (i.e., a Billion eV).
Anti-particles and particles instantly annihilate each other on contact, so anti-particles cannot not exist in our world besides for brief moments.
There's a theory that half of the universe is made of anti-particles (and the other half composed of regular particles). So you could say that the half we inhibit has few anti-particles in it.
They're also created all the time by radioactive decay which happens in common building materials. So yes, they'll be flying around your room now, but not going much further than that.
https://en.wikipedia.org/wiki/Bevatron