Mix them with a teaspoon or two of sterile moist sand, or sterile moist vermiculite (not soggy, moist like a wrung out sponge) and put into a tiny zip lock bag. Date and refrigerate.

When you are ready to sow, sow the contents of the bag, sand included rather than trying to extract the seeds.

Yup, they have to be moist, then cold, then planted. It simulates what would happen if left outside on the ground.