Dear Donia,
How do I frame old letters and clothing?
Q. Dear Donia,
A. Dear Kathleen,
What wonderful materials to have from your parents! It is a nice idea to get them framed but you will want to find someone familiar with conservation framing methods to ensure that the materials won't be damaged either from poor framing materials, poor mounting techniques, or light.
I don't know of anyone personally but you could contact the Seattle Art Museum's conservation lab. They would know of local framers who could do the work properly for you.
If nothing else, you will want to be sure that UV blocking glass or plexiglass is used to provide an initial barrier to light damage and then hand somewhere where there is little direct sunlight or bright electric light. Depending on what ink was used in the love letters, you may want to frame good digital copies so you don't lose the text over time.
Good luck with your project.