Hi from another Rachel with flatcoats!
My 2 flatties (5 months and 14 months) love helping in the garden - they prune all the plants (including prickly rosebushes!) and regularly chase each other around the mud, I mean lawn, with branches, twigs, leaves etc in their mouths! They also weed the borders,(ie dig everything up) and aerate the lawn - so helpful

The little pup has soon become accustomed to the same indignity his big brother endures - namely me opening his mouth and shaking stones out! We try to remove all pebbles and stones but they keep digging more up, and I don't like them to have bits of twig but they just go out and prune some more off. To be fair, they are very good at letting me take things off them, but they do tend to hide stuff and sometimes I have to have a really good feel around in their mouths to get it out!
As others have said, they will pretty much eat anything and everything, a trait I thought was confined to labs, didn't realise it was true for flatties but it is! Mine will respond to a firm 'leave it!' if you catch them first, and the older one who picks things up out on walks will now bring them to me in exchange for a treat, so there is hope!
Oh forgot to say they also love to help me muck out the horses, nothing better than fresh horse poo