Hi Sherry-
I think Mexican silver is very difficult near impossible to ID. Read the following from another site:
From 1948-1980, Mexican silversmiths used an 'eagle mark' along with other markings, letters, names and logos. There are a variety of different styles of eagle marks- left facing, right facing, forward facing, some with a great deal of detail and others are simple line drawings. Each eagle has a number stamped on it which may indicate the location or the identity of the maker. We know that a #1 was for Mexico City and a #3 was for Taxco. There was great variation and exceptions to the eagle numbering system. Because there were so many exceptions, the eagle is not a reliable dating or identification system. We do know however that it was in use roughly from 1948-1980. Some sources beleive the eagle mark system was in place as early as 1946.
This being said, go to this site and scroll down to page 240, maybe this will help.
Google BooksRegards- Byron