I noticed the nut had fallen off from my pickguard. Stopped at Home Depot today to find a replacement. Found a nut that fits, but it's larger than the original. Tried Menards also with no luck. What's the best place to find one of these? Thanks!
You might try a hobby shop that specializes in radio controlled stuff. They tend to stock a lot of small hardware, though it may be mostly metric. Your local guitar repair folks likely have coffee cans full of nuts and bolts. Take the pickguard off the guitar and take it with you. Have fun!