Pat is being somewhat complimentary towards Elizabeth. In modern America, horse farms are generally places for the privileged daughters of the wealthy who would be familiar with such a party. (There are also many poor, often Hispanic, stable hands but Elizabeth isn't a Spanish name and Pat is saying Liz's family owned the farm and not that she worked on it.)
Elizabeth tries to downplay her higher status as a gesture of friendliness. "It smells better here" is an oblique reference to the piles of shit the horses are continually producing.
Pat makes a friendly adult pun. Crap is a mildly offensive synonym for shit (i.e., horseshit and unpleasantness). It's also a synonym for bullshit (i.e., lies, inflated promises, and unpleasantness). She's commiserating with Elizabeth that it may smell nicer but Pat knows Liz must face unpleasant tasks and unpleasant people and lies on all sides.
Stivie makes a feminist point by stating that Liz doesn't only endure other's unpleasantness but also dishes out (i.e., serves) crap to others... Not that she's a bad person, mind, but that's she's powerful and willing to stand up for herself, which causes trouble for those who get in her way. Going from some to plenty underscores that she's winning whatever battles she's in.
Go team Liz.