This was a hard challenge. Serendipity can mean this - finding money growing on a tree. However, this SHOT was not serendipitous. You planted it and thus it violates the SPIRIT of the challenge, if not the rule. As to the pic itself - why not put the money on a tree bud? Like it's actually "growing on trees." Or something similar.
The lighting is kinda flat and overall the shot could use a bit more interest. I like the idea, but it could use refining.
This is the third staged photograph I've come across involoving an unlikely (i.e. unbelievable) discovery of cash. My problem with these staged photos in respect to this theme is that they go directly against the idea of serendipity. It doesn't take a lot of imagination to stage a photograph involving found money. However, it is a moderately interesting composition on an abstract level so this photographer has done it a little better than the others I've rated.