I love the look of those but what is the official name used for those so when I search for them I know what to call them.
Red treasury seals: Legal tender notes Red seals or Red Treasury seals... There are many different types of seals and colors from different eras of US Currency, large sized notes and small sized notes. Perhaps you are referring to the small sized notes when Red Treasury seals were used on Legal Tender Notes such as the $2 (Series 1928-1928G, Series 1953-1953C, Series 1963-1963A and $5 (Series 1928-1928F, Series 1953-1953C, Series 1963) denominations. Series 1928-D, $2 Legal Tender Note: Series 1963, $5 Legal Tender Note: A large size Series 1917, $2 with a red seal: