Hand Tools Archive
My first guess would be Euxylophora paraensis (Yellowheart), but my guess is based on grossly insufficient data.
A second possibility might be Pouteria spp. (Anigre).
Note that Anigre has a faint odor of cedar, while Yellowheart has a mild, unpleasant odor.
Does you stash include other tropical hardwoods, or just Appalachian hardwoods? For a positive identification, a much clearer picture of the end grain would be needed. That would require the end grain to be sliced very cleanly with a very sharp chisel and a photomicrograph of at least 10x. You can get that resolution through a microscope with a camera mount, or with an auxiliary lens attached to a cell phone.
I usually use Bruce Hoadley's "Identifying Wood" as a reference, but he doesn't provide any information on either of these species. An alternate strategy would be to take a sample end grain shaving, a sharp chisel or block plane, and a 10x loupe to your nearest Woodcraft or other hardwood dealer and compare your sample to what they have in stock.