A donation made in their name to their favorite charity might be nice.
Or if you live in a small town, make a cash donation to their public library for the purchase of more books. So many libraries struggle, either for materials or to keep their programs afloat. The performing arts struggle too. We are contacted by the Chicago Symphony Orchestra every couple of years for donations. Sad.
My in-laws had their 50th a few years ago. They asked for no gifts. But they still received all kinds of china, silver frames, embroidered throws, with their wedding date. The one thing they received that they enjoyed the most, were tickets to plays.