It is probably not American, with Belgian being a good guess. Check the barrel and breech for proof marks; if you see something that looks like a scrolled "L" or an oval with E L G in it, it is Belgian.
Maker? In the old days, many makers of inexpensive guns did not mark the guns with their names. In Europe, the guns were often the work of several small shops but in any case, no one cared and metal stamps cost money. (A comment could be made on the quality of a product the maker does not want his name associated with.)
Around 1890-1910 those guns sold here and in Europe for around $2-4 or the equivalent. They are sometimes called "Flobert" guns, but there are many variations and modifications of the original Flobert design, whose main feature was the use of a heavy hammer as a breechblock.
Value today? Probably $50 or so as a novelty. I strongly recommend against firing with any modern ammunition.