FODMAPS-friendly mayonnaise for those early-summer potato salads turns out to be rather easy to find. Most of the full-fat, real mayo on your grocer's shelf will work quite well! Always double check ingredients when you buy, in case they've switched sweeteners when I wasn't looking, but at the time of this writing, the following brands appear suitable for the FODMAPS elimination diet: Hellman's Real Mayonnaise, Cains Mayonnaise, Spectrum Organic Olive Oil Mayonnaise, Smart Balance Light Mayonnaise, even Miracle Whip.
Many of the fat-free mayos I checked were sweetened with high-fructose corn syrup, so read those labels carefully. Remember that regular corn syrup is OK on the FODMAPS elimination diet.