15gallon buckets that will hold a 5 gallon?

Does anyone know of a 15gallon bucket that is about the right size to hold a 5 gallon bucket in the top without too much work to modify it?

I am going to try growing a tree...

Where can I get containers of this size?

Home Depot, Lowes, Etc. These stores sell both 5 gallon buckets and 15 gallon tubs, so you can just go shopping and mix and match to get what you want.

Thanks

But I don't want tubs. I want 15 gallon tall round containers like the wide variety I see used in the food service industry. The problem being many/most of those I see have bung holes (not to be confused with a bunghole) or other crap on the top portion, or don't have a removeable lid at all, or have a funny shaped lid that you couldn't seal light out of if you placed a 5 gallon container in the top of it.

So that's the trouble... I want the small footprint of a round but tall container with a removeable lid that's flat without obstructions or funky shapes in the wrong places.