A 1928 $5 US Note should have a red seal, although it's possible the original color has changed due to time and/or exposure.
If the seal is definitely yellow, please check your bill and post a new question. The only small-size $5 bills with yellow seals were dated 1934 and were printed for use during WWII.
1928 $50 bills were issued as gold certificates and as Federal Reserve Notes but they're not the same. Please check the wording across your bill's top front as well as its seal color*; then see one of the following questions: "What is the value of a 1928 US 50 dollar Federal Reserve Note?""What is the value of a 1928 US 50 dollar gold certificate?"* Gold certificates have gold seals and FRNs have green seals.
Your United States Note is worth $20 to $50 retail, depending on how worn it is. 1928 was the last time $1 bills were printed as red-seal United States Notes.
This depends on the condition of the note. The better the condition, the more value. Generally speaking, a circulated note might be $120, whereas an uncirculated note might be $150 to $200
"A" is the highest series letter for 1928 $50 Federal Reserve Notes. "K" is most likely the Federal Reserve District letter. The series letter, if any, on US bills is next to the date. Please see the question "What is the value of a 1928 US 50 dollar Federal Reserve Note?" for more information on values.
The red ink and banner across its top front indicate that your bill is a United States Note and not a certificate. Certificates were at issued long ago for redemption in silver (blue seal) and gold (gold seal). Please see the question "What is the value of a 1928 US 2 dollar bill?" for more information.
There were no yellow seal two dollar bills. The red ink on your note was altered to look yellow.
A denomination is needed. Please look for questions in the form "What is the value of a 1928 A US [denomination] dollar Federal Reserve Note?" for specific information.
The value of a 1928 Silver Certificate dollar is worth at least the amount of the face value. There are 6 different 1928 Silver Certificates, the value depends on the grade of the certificate. The best way to determine the value is to have the note appraised by a professional.
Your bill is called a United States Note rather than a promissory note. There were eight different subseries within the 1928 series date; please see the question "What is the value of a 1928 US 2 dollar bill?" for specific information about values.
The green seal indicates that it's a Federal Reserve Note. Please see the question "What is the value of a 1928 US 5 dollar Federal Reserve Note?" for more information.
The green seal indicates that your bill is a Federal Reserve Note. Please see "What is the value of a 1928 D US 5 dollar Federal Reserve note?" for more information.
1928 $50 bills weren't issued as silver certificates. Please check the wording across your bill's top front; then see one of the following questions:"What is the value of a 1928 US 50 dollar Federal Reserve Note?""What is the value of a 1928 US 50 dollar gold certificate?"
Not every old bill is automatically a certificate so it's important to check carefully. If it has a gold seal and says "Gold Certificate", see the question "What is the value of a 1928 US 10 dollar gold certificate?" for values. If it has a green seal and says "Federal Reserve Note", it's not a certificate, it's a Federal Reserve Note. See the question "What is the value of a 1928 US 10 dollar Federal Reserve Note?" for values.
If circulated, retail prices range from $10 to $20 depending on condition.
1928-series $100 bills weren't issued as silver certificates, only gold certificates and Federal Reserve Notes. Please look at the bill's front to determine which you have; then check one of the following: "What is the value of a 1928 US 100 dollar Federal Reserve Note?" "What is the value of a 1928 US 100 dollar gold certificate?"
If your bill says "United States Note" it should have a red seal. The U.S. did not print yellow seal $2 bills with that date. Please post a new question with more details to help ID your bill.
1928 $50 bills were issued as gold certificates and as Federal Reserve Notes but they're not the same. Please check the wording across your bill's top front as well as its seal color*; then see one of the following questions: "What is the value of a 1928 US 50 dollar Federal Reserve Note?""What is the value of a 1928 US 50 dollar gold certificate?"* Gold certificates have gold seals and FRNs have green seals.