An unstruck blank is a round clipped piece of alloy that has not been through the upsetting mill and does not have an edge. A blank planchet is unstruck but has an upset edge.
Values for blanks and blank planchets vary but unless they’re the larger coins and higher denominations like dollars then they’re not worth much. Modern cent blanks are almost valueless with a few selling for a premium but not more than the grading fee that it cost to encapsulate the coin.