A knot of heads gathered about her, and Amy strained her ears to hear what was going on, for broken sentences filled her with curiosity, and frequent peals of laughter made her wild to share the fun.

One may imagine her suffering on overhearing fragments of this sort of conversation.
"She rides splendidly.

Who taught her ?" "No one.

She used to practice mounting, holding the reins, and sitting straight on an old saddle in a tree.

Now she rides anything, for she doesn't know what fear is, and the stableman lets her have horses cheap because she trains them to carry ladies so well.