Well both terms are unfortunate, but yeah basically just slang for the seeds that you find in shit weed. I don’t ever use the terms though, I just use “reggie” (meaning “regular weed”) for cheap weed and “seeds” for… seeds. Lol. As to why people started calling them beaners and "n****r weed is anybody’s guess. I’m sure the answer’s relatively easy to find but it doesn’t particularly interest me and I’ve actually only seen it online, nobody I’ve ever dealt with in person has said that to me.