I discovered that the pattern of the plates given to my Mom and her four sisters by my grandmother back in the 1940s is called 'Manhattan' and was made by US Glass. It was a popular dinner set made between 1902 and 1920. That early date makes me believe that these plates must have originally been part of a dinner set that was either owned by my grandmother (possibly a wedding gift since she was married in 1907) or maybe from a set that belonged to her mother.
My Mom and each of her sisters was given one of these plates. In our family it was used exclusively as the 'birthday cake' plate for the birthday of each of the six kids in my family. I have always wondered which company it was made by and the name of the pattern. I was very excited to find information about it online, and even better, be able to find matching bread and butter plates! Felt like I'd won the lottery!!