The "mortgage button" or "amity button" was a small ornamental inlay often featured on newel posts of a main staircase in the 19th and early 20th centuries, particularly in American and European homes.^{[citation needed]} It was used to hide joinery.^[1]

The name comes from the historical misconception that they represented a homeowner who had paid off their mortgage.^[2] According to tradition, the homeowner would arrange to have a button made of ivory set onto the newel post when the house was paid off.^[3] Another version is that a scrimshaw maker would engrave the date the loan was paid off onto a piece of ivory, which was inserted the newel.^[4]

One popular myth was that the decorative cap was concealing a deed to the house, or a mortgage document, which had been rolled up and hidden inside the newel post.^[1][2] According to writer Mary Miley Theobald, no such documents have ever been found, although house plans were found inside the newel post on one occasion.^[2]

Others have suggested that the ivory button on the newel post was a symbol of cooperation or brotherly love.^[5]