Jumble (with square)

Given the letters in a jumbled up word and a randomly chosen letter in the word, they must generate as many words as they can containing that letter while following these rules:

1. No plurals
2. No names
3. No acronyms
4. Must be at least 3 letters
5. Letters cannot be repeated

If the word length is n such that sqrt(n) is an odd number, I like to pop the jumbled word in a grid with the key letter in the center.