I think that looks excellent, Ross. It’s all very crisp and clean.
It doesn’t look like poster board to me. The grain is subtle, but it’s there. I can see where natural wood with dramatic grain would work well in the (largish) circles. I’d worry that using it in the background/field might compete too much with the lines and small squares. I guess wood with a grain pattern that looks more like a texture (like lacewood or the “snake skin” parts of sycamore) might add interest to the background without detracting from the geometry too much.