How can I repurpose old tongue and groove boards?

They could be stained into some great wall art

You can use them to make shiplap walls! http://www.hometalk.com/diy/decorate/walls/diy-ship-lap-wall-detail-7147289?expand_all_questions=1

https://www.pinterest.com/mwwallace/repurpose-scrap-wood/

You could make a beautiful wall-mounted headboard.

Depending how many you have. Bench, cocktail table, bedside cabinet, storage boxes, blanket chest, planter boxes. Possibilities are endless. Love to see what you make. Please post it here when you do.

I love the look of a wood ceiling...or you could cut them to the right length and use for signs or art after ageing the planks.

Depending on the hardness of the wood (i.e. oak or maple), cut out individual cutting boards, use a router to finish the edges, coat the outside with beeswax, run a ribbon through a router hole for hanging, and give them as gifts. If softer wood, such as pine, you could frame mirrors (especially those builder-grade mirrors they put in new houses) or make picture frames; paint to match decor or stain & varnish, and again give as gifts. There is no better gift than one you put together yourself - it shows how much you value the recipient. Of course, keep one for yourself, as a reminder of your accomplishment!

Build a playhouse for kids or a dog house for a dog.

Feature wall. Shelving. Sell it on marketplace.

Use them as a tabletop or cover a plain box with them.

I would suggest a table top too!

Hi Tink! You can check out this article for helpful tips. Hope this helps!

https://www.onlineflooringstore.com.au/ways-to-repurpose-wood-flooring-scraps/

They would make beautiful square planters fr out or indoors.

I used them to make wooden signs.