Foreign silver can be found quite easily and be a challenge to find out about the item, very satisfying though when loose ends are tied up. Use forums for questions and answers.
American Arts & Crafts is one area to look for nice items reasonably priced.
Continental silver is also worth looking at and could make a nice varied collection.
Colonial and Cape silver are also very interesting fields to consider
Scroll down to see some examples of foreign marks.
From top to bottom.
Germany Erich Iser (probably), Memel, on a Captains or Baltic spoon
Johann Christoph Drentwett, Augsburgh, clear marks on a cake slice
Germany Erich Iser, Memel (Memel is now Klaipeda, Lithuania) on a Captains or Baltic spoon
Robert.H.Taylor & Robert.D.Lawrie of Philadelphia 1837-50 on a brandy warmer or sauce pan
Georg Jensen, Denmark 1910-25 on a pair of tongs
France, Claude Francois Ricourt, Lille 1762/3 on a fiddle pattern teaspoon