Ok, maybe I can actually help someone on here for once.
You say these are frogs---are they tree frogs, "frog" frogs--like leopard frogs, cricket frogs, etc-- or are they toads? Knowing what you have living there in the side yard will make a difference on how to proceed. I know I tend to find a lot more tree frogs in places with available moisture than dry ones...it could very well be that you will find more frogs in your hostas than in your brush pile, yet if there's a layer of leaves/loose debris at the base of the brush, you will likely find toads rooted in under there during the day. Hard to say too, since I am not familiar with texas amphibs....
more info would help.
Glad you are concerned about their welfare. I personally worry about every frog and toad in my yard getting underfoot or underwheel.

Hi burntplants,
I wouldn't worry about disturbing the brush pile, if you have lots of other stuff around the area. They will just go elsewhere. I've found that my frogs and toads like weeds, hostas, daylilies, etc. Any area with lots of greenery will do.......along with the wetness of the area.
When you move the brush pile, just watch where you step and go slowly. I really think they all will be fine.