B.C.
My daughter turned 3 yesterday and is doing the same thing lately. Although with us, it's more like 10 stuffed animals, all the Toy Story characters, and a bunch of rubber farm animals and dinosaurs we bought at Toys R Us that she keeps in a basket. We take them all upstairs in the evening, then a lot of them end up in her bed (on a pillow next to her, or at the bottom of the bed), then in the AM we take a bunch downstairs to play with during the day. If one is misplaced or me or my husband put it somewhere else from where she put it, she'll know right the way. So no worries, it's perfectly normal what your son is doing. Probably just another phase, like everything else at this age. Good luck.