I checked my 1855 plain tridents and there is one coin that might possibly be a match. More than likely it is my imagination running amok.
This coin I had identified about 15 years ago or so and placed separately amongst my 1855s inasmuch as the colon is slightly closer than on others.
It does have a slightly "fatter" last 5.
Richard, maybe you can compare the colon spacing and see if there is a match there. If so, then that might be an identifier if indeed there is something ornate in the breast plate.
If it is just a closer colon spacing, then it is merely a die variety. If indeed, in addition to the colon spacing, there is also a more ornate design on the breastplate, then we have identified a new reverse die.
Obviously the ideal situation would be to find a high grade example and either confirm or refute this observation.
Again, despite the definite difference in the colon spacing we might be in total fantasy land regarding any design on the breastplate.