Green plastic USMC uniform buttons

Hi all! I recently acquired a cache of vintage military items from an estate sale. Apparently, both husband and wife were in the Marine Corps from the 1950s - 1980s. One of the items I'm having difficulty identifying is a bunch of green plastic buttons bearing the USMC insignia. All I've been able to find online that's similar is black buttons or green WWII bakelite buttons. The ones I have definitely aren't black and they don't seem like bakelite, either (plus, the backs are different from the WWII variety). I suspect they're Vietnam-era, plus or minus a few years. It's just odd that I can't find ANY pictures or reference of similar items online. So I'm hoping the experts here can help me. Any clues greatly appreciated!

https://www.milsurps.com/images/impo...IMG_1289-1.jpg
https://www.milsurps.com/images/impo...IMG_1290-1.jpg

Welcome to the forum, give us a minute and there's a few here that will know.

Thanks for responding, Jim! I'm in no hurry. I've got several minutes to spare. :) I'm just hoping someone can come up with an approximate date range that these types of buttons were used. And maybe what type of uniform. I'm guessing the larger buttons were for men's uniforms and the smaller ones for womens. Thanks!

Maybe I stumped everybody. Or it's too boring of a question. :(

Sometimes it takes a bit...more than minutes for sure... Nothing's boring, we enjoy all of it.

Thanks. :)