American Thread Company, from the early 1940's through the 1950's, employed a number of pattern promotion techniques. The pattern promotions were to entice the user to purchase their thread. Along the lines of .... love the pattern .... purchase the thread. Patterns might be advertised as 'mail order' through magazines or newspapers, or handed out at the local 'yarn shop'.
A search of the newspaper database brought another example in this newspaper clipping from early 1948 requesting the reader send a request to receive the pattern by Mail.
Note the colorful description here -- rather a play on the other syndicated patterns of Alice Brooks, Anne Cabot etc. - "When friends come for tea, your lace tablecloth adds a special welcome. Here's a lovely cloth of square motifs with daisy centers as white, informal and graceful as a field of daisies. These lacy pieces make cool summertime needlework for crocheters".
It would be my guess that this pattern was a specific promotion for the Gem Mercerized Crochet Cotton; which American Thread introduced in January of 1948.
If you'd like to put this one on your hook, it's available in the shop at the link above.
Thanks for dropping by,