The dry flower made me think that it was from a memory anyway, before I read your last line. I know this is often done to keep a souvenir from a special day/memory.
The word "falls" made it quite vivid to imagine the flower had been forgotten, and suddenly, when the pages of the book are opened, it falls out.
The description of the bible itself, with the yellow stained pages through age, was very well portrayed. This made me think that it is an air loom perhaps, from someone who has passed it down to younger generations.
I also think it gives away a bit of personality for the person who is being remembered here, showing us that this bible clearly meant a lot to them, and was a big part of them.
Your poem can actually be taken many ways, which is why I love basic poetry with not much detail and description.
You can take it that the bible does belong to the other person, and the flower creates a memory of a day in the past. Or, the bible might not be the other person's, it could be the author's bible, and because this is a thing they hold, read, carry, many places, they found it the safest place to carry this flower.
Also, the flower falling, could be a metaphor, it could be the flower representing a person, and falling representing the death of that person. Which again would tie in with memories of that someone.
I'm absolutely in love with this. With just these few words you've managed to create a whole scene. A lifetime, really. Just picturing when the flower was first given/put there, when the Bible was, perhaps, still new. You leave the reader wondering who the Bible/flower belonged to. A loved one? Mother? Grandmother? Lover or sibling?
A sad, beautiful write.
I always enjoy reading your work.