I’ve seen these Pyrex mugs a few times on Ebay. My thought was that they were part of another beverage server set that Pyrex was known to make which featured six of the 1410 style mugs like these plus a carafe. However, I haven’t seen the full set yet – we won’t put them in the pyrexlove ref until we find out what they are.
They have a really unusual color combination, bands of baby blue flowers on an avocado verde base. I’m not sure why they chose this particular color scheme – I was thinking maybe the carafe would provide more answers. There are four different flower bands, all of them different and interestingly not equidistantly spaced. A Flickr reader has noted that perhaps the 4 bands correspond to the different seasons of the year. So, the top row would be Summer (roses?), the next one would be Fall (mums/asters?), the next would be Winter (holly perhaps?) and the last one would be Spring (the flowers from the spring blossom pattern).