Hi Matt ...
To my experience in collecting counterstamped coins, going on thirty years now, it's very difficult to attribute the great majority of those which only have initials. That said, initials that are set in relief, a cartouche or touch-mark, do offer some hope for the studious collector.
The "T.B" c/s may be the mark of a silversmith, yet it appears larger than most I've seen. Other prospects are toolmakers, tinsmiths and other craftsmen; this, as opposed to merchants. The mark would have to be matched with that on a product, say a silver bowl or a wood plane. Some initials are more common than others ... The letters Q, Z, and X being less common and thus offering a greater prospect for attribution.
Take a look at the silversmith website, below. There are a few "T.B" hallmarks that look similar to yours, but they don't match. The letters on yours are larger, I believe, and more likely a toolmaker's mark, I suspect. (If you're ever in an antique shop, having old tools, especially wood planes, look for the maker's marks on them.)
http://freepages.genealogy.rootsweb...itials/t.htmI see c/s's listed on
ebay, constantly. Some sellers wrongfully attribute them, hoping to score a sale. One such item was a
Shield nickel that simply had three initials; this, akin to your 1829. The seller found a sutler with the same initials and "attributed" it to him. He got offended when I politely asked him the basis for that attribution and questioned his implausible rationale. Buyers beware!
As to the question of value, regarding counterstamps, one has to consider the date, variety and condition of the host coin. Experience tells me that common date large cents (the most often seen host coin) like your 1829, lower grade, will sell in the $10-$15 range. Those like your 1819, having unattributed initials set in relief, will sell in the $25-$30 range. If properly attributed, matched to a toolmaker or silversmith, that value will double or triple.
You can look for books, directories, on 19th century toolmakers, silversmiths and many other occupations that will help with attribution. Your local library may have some or be able to secure copies from other lending libraries. Google has many older reference books available online. I will warn you though that this pursuit, the attributing of counterstamps, can be highly addictive!