What is the value of a 1970s penny?

If you found it in change, 1 cent.

If it's in a mint set or proof set:

With no mint mark and in uncirculated condition it's worth $0.25. With D mint mark and in uncirculated condition is worth $0.10. With S mint mark, large date in uncirculated condition is worth $0.15, proof is worth $1.00. With S mint mark, small date in uncirculated condition is worth $30.00, proof is worth $60.00.