The ads would be owned by the companies that produced the silverware and commissioned the ads. I doubt that they would be copyrighted, since any unauthorzed copying would most likely be pursued as trademark rather than copyright infringement.
I don't think your proposed use, re-printing the old ads, would be considered trademark infringement.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
While the owners of the copyright in the advertisements will likely not object to your re-publication of their advertisements, they may. A niche genre of books about old marketing material exists and, for works not yet in the public domain, licenses are granted to permit the material's re-publication.
Even though "old," the ads you want to publish on your website may still be protected under copyright law, depending on when they were first published and whether they were published with a copyright notice (among other factors). Determining whether any particular one of them is still under copyright requires a complicated analysis. I suggest that you buy a book on the public domain (one good one is at ) and a book on how to clear the rights to a copyrighted work (see ).
Your risk of monetary liability for re-publishing the copyright-protected ads without a license is likely quite low. Nonetheless, it is not non-existent. You need to learn a bit more about how the companies in this field deal with their legacy products.
Mr. Ballard's discussion of copyright issues is quite thorough. I would like to add the following to Ms. Koslyn's discussion of trademark issues.
Because your use of the marks in the ads would be to describe the products of the owners of those marks (rather than your own products), your would have a "nominative use" defense to any allegation of trademark infringement. The link below is to the Electronic Frontier Foundation's Internet Law Treatise discussion of this topic.
Disclaimer: This post does not constitute legal advice and does not establish an attorney-client relationship.