Don't toss a good straw hat that has gotten out of shape over the winter! Almost all straw hats can be put back into shape by wetting them slightly, then gently pulling and pushing them into the proper shapes before letting dry. It also works for hats that say they are "paper and polyester"! Straw and panama straw actually LIKE getting some moisture, so they don't crack.
If a fine straw or panama DOES crack at the crown or at an inconspicuous place, you can mend it by using clear plastic adhesive tape on the inside of the crack. The mend will be invisible from the outside and you can get a bit more wear out of the hat(s)!