My guess is that it is a brass backing plate off the upper, decorative portion of a crown/tiara shaped hair comb, and that on one side of the holes were the comb and on the other were more adornments. Thus this was sandwiched between.
How flexible/rigid is this? It looks like copper, does that seem right in person? Also it appears there may be little bits of silver plating remaining, does that too look correct in person?
I'm no decorative hair accessory expert or anything but if my guess were accurate, based on the size, style, and the nature of the corrosion, I'd venture 1875 +/- 15 years. The style has never "gone out of style" from what I can tell, but this thing has age to it.
Having said that, the fact that nhbenz gave such a weird and oddly specific suggestion gives me pause. I don't know if I've ever seen a case where he's been wrong on something. I'd encourage you to do some searching on his idea too, as mine was only a guess.
Mine was a complete guess as well (and I've been wrong plenty, but Thank You mlc!). The little I was basing it on is that it was found near an old church, where a fair number of these were used. Just a simple search to show the general idea of what I was thinking, which again could be wrong: gothic sanctuary chandelier - Google Search
I'm thinking it might be a vintage ladies 'collar necklace.' The 2 holes on each end would have held the connection piece that went around the neck. The center hole would have held a hanging decorative piece.