Antique Sideboard/Commode/Buffet/Dresser: Walnut with Solid Marble Top

This three-drawer sideboard/commode/dresser/buffet was passed down to me from my grandmother's house.  She kept it in her dining room, which makes me think it is a dining piece, but it may be a dresser instead.   I think the wood is walnut.  The top is one solid piece of white marble.  The piece is quite heavy due to the marble top.  The legs are clawfoot with an intricate wood design.  The piece has keyholes in each of its 3 drawers, but I do not have the original key.  The original knobs were slightly larger, but we replaced them with smaller knobs due to wear on 1 of the original knobs.  We still have 5 of the original knobs if that would affect the value of the item. There are no tags or indications of brand anywhere on the item.  Its condition is very good with slight discoloration of some areas of wood, some scuff markings inside drawers and on 1 claw leg, and replaced wooden knobs with slight coloring of where old knobs were before. The piece measures:Whole piece together (from floor to top of marble top):  43" tall x 22" deep x 55 1/4" longSolid Marble top:  55 1/4" long x 22 1/2" deep x 3/4" thickWooden section:                  Including legs:  42" tall x 21 1/2" deep x 53" long (at longest part)            Excluding legs:  25 1/4 tall x 21" deep x 53" long (at longest part)Legs:  16 1/2" tall x 5" deep (at widest part at top) x 5" long (at widest part of top)Drawers:              Top drawer:                      From outside edge of drawer:  47 3/8" long x 18 3/4" deep x 4 1/2" tall                    From inside edge of drawer:  46 1/4" long x 17" deep x 3 1/2" tall          Middle drawer:                    From outside edge of drawer:  47 3/8" long x 18 3/4" deep x 7" tall                    From inside edge of drawer:  46 1/4" long x 17" deep x 6 1/4" tall          Bottom drawer:                    From outside edge of drawer:  47 3/8" long x 18 3/4" deep x 7" tall                    From inside edge of drawer:  46 1/4" long x 17" deep x 6 1/4" tall