Very rare Confederate Merrill carbine variant bullet. Cannonball Guy helped me eliminate anything newer than the Civil War. It's an unlisted variant.
No logical explanation of how they got out in the middle of a barren field, next to an old spring house, except since a lot of southerners were just plain out of money at the end of the war, and went north for employment, someone may have just dumped them.
Or, a Yankee soldier finally decided to dump his souvenirs. I like when that happens. I have found more plates at house sites than battlefields.