The pure OG Kush is a clone-only strain but you can get some killer seeds with OG Kush in the mix. Kushberry is OG Kush x Blueberry from DNA genetics. Kushage is OG Kush x S.A.G.E. from TH Seeds, MK Ultra is OG Kush x G13 from TH Seeds. I would personally choose MK Ultra if you want something closest to the pure OG Kush because G13 has very little flavor so the taste and smell would be closest to the pure version. You can get beans for all these strains on drchronic.com.