The Lark - E. Nesbit

It's 1919 and Jane and her cousin Lucilla leave school to find that their guardian has gambled away their money, leaving them with only a small cottage in the English countryside. In an attempt to earn their living, the orphaned cousins embark on a series of misadventures - cutting flowers from their front garden and selling them to passers-by, inviting paying guests who disappear without paying - all the while endeavouring to stave off the attentions of male admirers, in a bid to secure their independence.