Patriotic embroidered postcards, made in France, were popular souvenirs made for soldiers during WWI. This one is unusual in that has the month "April" as well as the year "1917." It features an American flag. Embroidered American flags seem to be much less common than British and French flags.
This embroidery on this postcard is quite faded, making it less valuable than a brightly colored card. It still is very clean and collectible, however. The embroidery is on cloth inserted between an embossed paper frame and a paper backing. The embossing on the frame consists of horseshoes in the corners and four-leaf clovers on the sides--two good luck symbols. On the back is printed "Fabrication Francaise."
More information on embroidered postcards:
Gabrian Silk Postcards
Propaganda Postcards of the Great War, Silks (embroidered postcards)
Love Tokens from the front
The Church San Sebastian, Manila
25 minutes ago