Can we write SOSL statements in triggers

Yes, we can write SOSL inside triggers.There is no such restriction.

Code:

trigger trg_AccountSOSL on Account (before insert, before update) {

List<List<SObject>> searchList = [FIND 'map*' IN ALL FIELDS RETURNING Account (Id, Name), Contact, Opportunity, Lead];
List<account> myAcc = ((List<Account>)searchList[0]);

system.debug(myAcc[0].name);
}