Only one Hosta has flowered this summer.
Is it worth saving seeds from it if they form?
Or does a Hosta need another Hosta's pollen?

A fertile flower does not need another flower, and if a pod is produced you should collect the seeds when the mature pod starts to crack open.

Maybe that should say COULD collect the seeds. While they will be fertile, they may, or may not, produce anything remotely interesting, depending on the particular plant.

Thanks.
I am an inveterate seed collector, so will save them and see what happens.

I love collecting the seeds and planting them, even if all I end up with is green(the only thing I have ever gotten). I have lots of seed pods right now, just waiting for them to mature a bit more.

Green is good!