We went to Mason City and Clear Lake expecting terrible chain food (Applebee's, Long John Silver's and the like), but we did find three surprisingly good places:
Cancun Mexican Restaurant
2751 Fourth St SW (Hwy 122), Mason City
1801 US Hwy 18 E, Clear Lake
Cancun is a pretty normal Mexican restaurant -- if you live in California. The spice level is dumbed down to Midwestern levels, but with the addition of some salsa picante you can make up for it -- and the portions are absolutely gigantic.
The Rose Cottage
114 N 3rd St, Clear Lake
The Rose Cottage is a tea-room that offers two lunch seatings daily, 11 AM and 1 PM, though you can usually get food to go outside those hours. There are six or seven light daily specials, ranging from curried chicken salad to a "Greek Wrap" which is like a gyros. Be aware that the "fruit" promised on the menu may be "fruit salad" (what non-Midwesterners call "ambrosia") or even lime fluff.
113 W Main St, Fertile
Open only for breakfast and two nights a week for dinner, the Fertile Cafe is the archetypal small-town cafe, where everyone knows everyone else, regulars have their own tables, and the town gossips ply their trade. The French toast (four slices for $1.95) is incredibly good, as are the biscuits and gravy. The coffee is OK but it soaks up the breakfast very well.