I have a little project in the works and it required me to find some vintage linen napkins. I thought to check out etsy's vintage wares and ta-da! Linen jackpot.
You'll see the ones I bought soon, but here are some other lovely things (click on the photos to buy). From stripes to roosters (for "cocktail" napkins, har har) to varying shades of pink and peach, any of these would look lovely around your summer table.
Aren't they just lovely? I did a search for "linen napkins" under the vintage section and there are hundreds of affordable options. Happy shopping! (And if you buy anything, I want to see pictures!)