20-year-old Whalley made three subsitute apperances for Chester City after being awarded a pro contract back in 2004/2005 season but he was released in May 2005 and then joined Runcorn FC Halton.
Whalley then joined Witton in March of this year and came back to haunt Runcorn FC Halton by scoring in a 4-0 win.
Whalley has attracted interest from several league clubs after some stirling performances for Witton Albion, in which they are challanging near the top of the Unibond Premier Division.
Gradi watched Whalley play in Wednesday night's 5-1 win over Tranmere Rovers in the Cheshire Senior Cup.
Gradi said "I believe there is a bit of interest in him from other clubs, but Witton's manager got in touch and asked if we'd have a look at him.
Witton manager Vince meanwhile said "I have no idea whether Crewe will be interested in him, but from my perspective the trial will only do him good.
"It gives him a chance and gives Crewe the opportunity of one of the best young talents around."