Lots of lawyers among the founding fathers -- Jefferson, Madison and others.

The Congressional Reference Service on the occupations and education of the 108th Congress:

Occupations

As has been true in previous Congresses, law and business are the dominant professions in the 108th Congress. Other professions include public service, education, agriculture, and journalism. A closer look at the prior occupations of Members of the 108th Congress also shows:

eight medical doctors (including a psychiatrist), three dentists, two
veterinarians, an optometrist, three nurses, one pharmacist, and three
psychologists;

five ministers;

35 mayors, 13 state Governors, 11 Lieutenant Governors (including two
Delegates), two state first ladies (one of whom was also the first lady of the United States) and one territorial first lady, two former cabinet secretaries, two state supreme court justices, and a federal judge;

a president of the National Conference on State Legislatures and 274
(232 in the House and 42 in the Senate) former state legislators;

112 congressional staffers (including 10 congressional pages), 14 White House staffers or fellows, several former executive branch employees, a former aide to the Secretary of Defense, a former deputy administrator in the Veterans' Administration, a former deputy assistant Secretary of State, and a former ambassador;

four police officers (including a Capitol policeman), two state troopers, two sheriffs, two volunteer firemen, two probation officers, and a border patrol chief;

two FBI agents and one CIA agent;

two physicists, two chemists, a biomedical researcher, a geologist, and a microbiologist;

six Peace Corps volunteers;

an astronaut, a professional magician, a semi-professional musician, two broadcasters, a television sportscaster, a television reporter, a
motivational speaker, a commercial airlines pilot, a corporate pilot, a flight school instructor, a major league baseball player, a major league football player (who was also a college football coach), a florist, a librarian, two vintners, two auctioneers, two jewelry makers, a steelworker, a carpenter, an ironworker, a paper mill worker, a meat cutter, a river boat captain, a hotel bellhop, a taxicab driver, a race track blacksmith, and a "jackeroo" (cowboy) on a sheep-cattle ranch.

Education

As has been true in previous Congresses, the Members of the 108th Congress are well educated. At least 399 Members of the House and 97 Senators hold bachelor's degrees; 124 Members of the House and 19 Senators have master's degrees; 175 Members of the House and 59 Senators hold law degrees; 18 Members of the House have doctoral
degrees; and 11 Members of the House and three Senators hold medical degrees.

In addition, there are two graduates of the U. S. Military Academy, one in the House and one in the Senate; one Senator is a graduate of the U.S. Naval Academy; one Representative (a woman) is a graduate of the U.S. Air Force Academy; five Representatives and three Senators were Rhodes Scholars; one Representative was a Fulbright Scholar, and one was a Marshall Scholar.