Sawbuck is not a common word in Canada (for my generation anyway), but may be more common south of the border — in the U.S. (not Mexico). Buck, a diminutive, was a common Canadian reference to the one-dollar bill, until the paper version was replace with a one-dollar coin (featuring an engraved Loon), then the slang “loonie” became popular.
SAWBUCK: Originally slang for a sawhorse, fashioned in the 18th century by lashing together two pieces of wood into an “X” shape. With an X-shaped support at each of two ends, the contraption served to hold wood for cutting. With the advent of the U.S. 10 dollar bill, which bears the Roman numeral X, “sawbuck” became slang for the bill, as people associated the shape with the sawhorse. The slang term “buck” originated in the mid-19th century in reference to the dollar.1
To ”buck wood” is the process of cutting a long log or tree into shorter sections, usually in preparation for chopping into firewood. I know this because I recently became enamoured with chainsaws.