A type of cards known as hanafuda cards in Japan which are used for a range of different games that require associating pictures (there are no numbers on the cards).
The artwork for this emoji shows the Full Moon with Red Sky card, but could theoretically display any of the available cards.
Flower Playing Cards was approved as part of Unicode 6.0 in 2010 and added to Emoji 1.0 in 2015.
U+1F3B4
? Flower playing cards