Answer: A posie would have been simply a little bouquet, a tiny handful of flowers. The Victorians elevated the status of the little home-made bouquet and used decorative posie holders (now a collectible) and they sometimes composed their bouquets according to the "language of flowers" (now enjoying somewhat of a revival). Earlier, a posie was simply a fragrant bouquet held to ward off the stench of day to day life before modern plumbing and santitation practices.
Here is a photo of a particularly elegant posie holder, to give you an idea of the scale involved; it is only three inches tall.
Unfortunately, a quick search did not bring up any photos of actual posies.
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