When my Father died, the mortician showed us caskets and then told us he wouldn't sell us one. He told my brother (a cabinet maker)to go home and build one himself for his father, and he did as he was told.
As a covering in the casket was a quilt my Mother had made
Since then my brother had made a number of caskets. He made one for my husband and again a quilt I had made was used inside.
Our mortician said the flowers will be on the casket just to carry it a very short distance into church and the people will already be inside, so they won't even see flowers. Once inside the church the casket is covered with a white cloth until he service ends.
I suspect my husband's family may have felt it strange not having flowers.
My feelings: please give me flowers when I can still enjoy them!
I think your idea of a quilt covering the casket is great