Photo of specimen with a US quarter (~24 mm diameter) for size reference. Please help identify what left behind this casing. It was found in middle of the yard, approximately 25 feet from nearest tree but was near a lumber pile if that is relevant. Located in south Central Colorado. Appears to be a winged beetle of some kind
Note: I'm no expert and not even from North America, so take this with a grain of salt.
I think this is a May Beetle (Phyllophaga genus) or possibly a Junebug from the widespread scarab family of beetles. The adults range in size from about 12-25 mm (0.5-1.0"). A distinguishing characteristic of the scarabs is the linear ridges along the wing-casings and the beautiful stippling of the elytra (wing casings). Unfortunately you seem to have lost the antennae, which, if they are scarabs, have an enlarged club-shaped tip. It has an exposed scutellum and straight edges to the elytra, which are also features of the May beetle/Junebug family (Melolonthinae)
The Scarab family are a common pest of grass-lands and trees world-wide, and this genus is no exception - the name literally translates as "leaf-eater" (phyllo - leaf, phaga = eater).