The Frugal Housewife mentions (in 1830) using peach leaves to flavor a pudding– this is certainly the first I have heard of this flavoring. Some half-hearted googling turns up some other mentions, most quite old, of flavoring with peach leaves. It sounds like they may taste of almonds.

A contemporary herbal mentions the leaves as having many positive effects, including “[i]n large quantities, they act mildly upon the bowels, securing mucous discharges without pain; and in this act many times leading to the expulsion of worms in their nests.” Eek!