Octagons have 8 sides. Grandmothers Flower Garden uses hexagons which have 6 sides.
If they are octagon blocks, google image search "octagon quilt". You will need either squares or triangles to fill in between the octagons, depending on you lay them out. You can see from the google search what I mean.
If they are hexagons, then GFG is a good use. Google image search "gfg quilt" for examples.