Hens will quite naturally clean up a broken egg- better the hens eat it than the weasels or rats get at it. If you have a hen that is actually breaking good eggs, then try putting an eggshell in the nestbox with a yolk of english mustard. This tends to work quickly and well.
Are your nestboxes smooth sided, or have they got bits of framework in the corners? This can be a cause of cracked/broken eggs, a good thick layer or straw and/or shavings and obviously enough nest boxes for the number of hens(1 box to 7 hens is the maximum). Give them Oyster shell for thicker eggshells.
Golf balls will not fool your hens, and might make them go off and find somewhere else to lay. Your feed merchant will have china eggs. A toyshop near us has brown rubber eggs that look very convincing for 50 pence!
If the problem persists after a couple of days, despite mustard etc, then you will have to identify the culprit or the others will pick up on this habit. Find the one with egg on her beak, and take the neccessary steps.
Best of luck, Ross