There are two very accomplished wood ID guys who hang out on the Woodbarter forum (woodbarter.com) -- and there's a subforum devoted to the subject.
Paul Hinds runs his own "HobbitHouse Wood ID site" --
HERE -- with a huge number of wood types photographed and identified. He's also written several articles on the anatomy of wood, but they are beyond me.
Just from looking at the pix on his site, I can tell yours is unlikely to be pecan (the end-grain photo of yours shows the little holes are more or less uniformly spread across the year-rings, where pecan has them concentrated in one side of each year-ring ... I think the technical terms are "ring diffuse" versus "ring porous").