I was browsing around the internet last night and came across the Lawrence County, MO genealogical society site which wasn't loading for some reason. Well, I went back this morning and it loaded up just fine. I am sure glad it did because it's led me to a treasure trove of information on one line of my family.
It had a link to the Missouri Death Certificates online images and so far I have found at least 6 ancestors in my Hazlett lines. I've found great-great-grandma Mamie Kate Wallace and her husband John Wesley Hazlett who I already had some information on thanks to my grandmother. I have also finally, after years of trying, broken through the brick wall and found John Wesley's parents (and their death certificates too!). Another great find was the death certificates for my great-grandmother's parents on the McDonald lines.
I highly recommend that if anyone has relatives who have died between 1910 and 1959 in Missouri to go visit this site. I can't wait to comb through my tree and see who else I might find in this database!