Bits and bobs

A very ordinary-sounding British phrase with a surprisingly undocumented past. "Bits" plainly means small pieces or items, but why "bobs" specifically, rather than any other rhyming word, isn't explained anywhere in the historical record. One loose theory ties it to "bob," old slang for a shilling, implying a jumble of small odds and ends worth about that much, but there's no real evidence connecting the two senses beyond the shared word.