One of my previous labs used to tidy up his toys from the garden, he’d bring them in and put them in the toy box before his walk. I have absolutely no idea how I taught it, it’s a nuisance as it was really useful. Obviously it was no help at all telling you that .
A bit like this. It kinda misses a bit part - clicking when your dog turns towards the tray with the toy in their mouth, and incremental steps towards it. But maybe this dog just skipped over that part
I emptied Maisy's toy box and together we filled it back up one by one. Firstly I put the toy 'In the box', showed her how, guided her, then a treat when she did it. Her aim wasn't great at first but she got a treat for each effort. Now when we play 'In the box' she takes things out of the box just so she can put them back for a treat. Sneaky.