back in the 1960's folk's would buy a lid.?

The term 'lid' of marijuana goes back to the 60's. Back then you could buy a 'lid' or a 'can' of pot. The can was approximately 1 oz, the lid was 1/8 oz. The term came from the practice of breaking up a brick (a kilo or later a key) of tightly packed marijuana and storing and selling it in Price Albert tobacco cans. A can held approximately one ounce. The lid would hold approximately1/8 oz. No one weighed it really, it was all done by eye. By the early 70's the term can had gone away and the term lid referred to an ounce. The term nickel or dime bag was still used in the 70s too. But by that time the amount of pot in the nickel ($5) or dime ($10) would vary - though the price was still $5 or $10. But if you bought a 'baggie', it would contain an ounce and the price would vary. In the 60's a bag was a bag was a can was an ounce and the price for the ounce was 5 or 10 depending on quality.

Yeah, about 28 grams or three fingers whichever worked. About 10 bucks.

Good question. People coin terms all the time from some observed habit or whatever they see someone else doing. Back then people tried to ":one-up" each other when it came to being "clever" and "cute" with one's vocabulary.