It may be a "Struck Through" error. Although
Grease Filled Dies are somewhat common, it is something worth keeping. The Kansas 25c that has the filled "T" reads "In God We rust" indeed has value for collectors judging by the
ebay prices. However, I pulled an 88 cent I have with no FG, and believe it an abraded die. The scratches on mine show no evidence of a strike through. I cannot tell from your pics, but suggest filing it for future. If you happen to find another, send the best one in to an expert.