If your family eats grapefruit (or any other citrus with seeds), you can plant the seeds and grow bonsai citrus trees! Now citrus trees don’t make great bonsai (the leaves are a little on the large size), they do make reasonable bonsai. And they grow pretty fast. John, Molly and Annie E. have a citrus that they worked on at our repotting workshop two years ago – a very nice tree.
The seeds don’t require stratification. Just put them in some soil and keep them damp (not wet). If you have a heat mat, that will assist with the germination. Lots of seeds don’t like to germinate if the soil is too cold. But, I have germinated grapefruit without bottom heat. – Karl