Black was worn for mourning but that does not mean that all black clothing was worn for mourning. Usually, mourning clothing was sedated and an entire outfit made of lace does not sound like mourning attire.
The black lace head covering sounds like a mantilla which is a lace veil that comes down to the shoulders. In Spanish cultures, young girls wore white mantillas while married women wore black. Mantillas were popular head coverings worn for church in the United States during the 1960s and 70s and not limited to Spanish cultures.
If you are trying to learn about those garments, try to find out what kind of material it is made from - what kind of lace is it? In the past, lace was made of linen, silk, later cotton. Manufactured lace can be made of synthetic fibers. So the material can give you a clue. If it is synthetic than it was made after 1935. The style can give you a clue as well. Look at the length and width. Very wide skirts were popular in the mid-1800s and again in the mid-1900s. Tiny waists and wide, ornate slips were all the rage from between 1947 - 1963.
For help with understanding the old clothing you found, contact Virginia City's The Way it Was Museum or the Nevada Historical Society in Reno.