From an O.Henry story about a rancher and his guest having
conversation while snow-bound:

"It's like you had a wife and left her in the morning with the same old blue cotton wrapper on, and rides in of a night and runs across her all outfitted in a white silk evening frock, waving an ostrich-feather fan, and monkeying with a posy of lily flowers. Wouldn't it make you look for your pocket compass? You'd be liable to kiss her before you collected your presence of mind."


I have always thought of a "posy" as a single flower, given
as a token of admiration to a girl or woman. So I was surprised to find it more commonly means several flowers arranged with an effort at artistic effect.

Source: WordNet (r) 1.7

posy
n : an arrangement of flowers that is usually given as a present
[syn: bouquet, corsage, nosegay]


Source: Webster's Revised Unabridged Dictionary (1913)

Posy \Po"sy\, n.; pl. Posies. [Contr. fr. poesy.]
1. A brief poetical sentiment; hence, any brief sentiment,
motto, or legend; especially, one inscribed on a ring.
``The posy of a ring.'' --Shak.

2. [Probably so called from the use of flowers as having an
enigmatical significance. Wedgwood.] A flower; a bouquet;
a nosegay. ``Bridegroom's posies.'' --Spenser.

We make a difference between suffering thistles to
grow among us, and wearing them for posies. --Swift.