I hope someday to write an Old West novel of some kind. These are some terms that could be useful.
1.Arbuckle's ~ slang for coffee, taken from a popular brand of the time. "I need a cup of Arbuckle's."
2.Between hay and grass ~ neither man nor boy, half-grown.
3.Big bug ~ important person, official, boss. "He's one of the railroad big bugs."
4.California widow ~ woman separated from her husband, but not divorced. (From when pioneer men went West, leaving their wives to follow later.)
5.Crowbait ~ derogatory term for a poor-quality horse.
6.Difficulty ~ euphemism for trouble, often the shootin' or otherwise violent kind. "He had to leave Texas on account of a difficulty with a gambler in San Antonio."
7.Dreadful ~ very. "Oh, her dress is dreadfully pretty."
8.Fetch ~ bring, give. "Fetch me that hammer." / "He fetched him a punch in the nose."
9.Flannel mouth ~ an overly smooth or fancy talker, especially politicians or salesmen. "I swear that man is a flannel-mouthed liar."
10.Get a wiggle on ~ hurry.
11.Gospel mill ~ a church.
12.Hobble your lip ~ shut up.
13.See the elephant ~ originally meant to see combat for the first time, later came to mean going to town, where all the action was.