From the wiki:
“Circulated current-issue $2 bills (dates 1976 and later, with green seals) are worth $2. If they are in crisp uncirculated condition the retail value could be double that.
Older U.S. Notes with red seals can be worth more. Some typical retail values are:
1928: $3–10 circulated / up to $50 uncirculated
1928A: $5–10 / 225
1928B: $20–85 / 700
1928C: $2–10 / $100
1928D: $2–8 / $30
1928E: $2–12 / $65
1928F,G: $2–8 / $25
1953, 53A,B,C: $2–3 / $8
1963, 63A: $2–5 / $4
Busting the myths:
US $2 bills have NEVER been discontinued or recalled and are STILL acceptable for use anywhere any other denomination is valid. They are still being printed (latest series dated 2008) although in much smaller quantities than other denominations. ”