These seem like some neat tileset/background concepts here. Don't often see Donkey Kong Country locations in the style of a Mario game.

I will say however that they could probably do with a bit more variety here. The bramble one has quite a bit of it with all the flowers and decorations, but the lack of diagonal brambles feels like a bit of a missed opportunity. And while the swamp one is cool, the number of tiles to play around with seem very low compared to the bramble one, which may make it tough to create a visually varied level using them.

Maybe a few vines, barrels, slopes, etc would help there?

Either way, it looks good, and the backgrounds seem like they work well.