I birded Weston Bend State Park in Platte County for about 7 hours Saturday (May 11). Highlights included Veery, Gray-cheeked Thrush, Red-breasted Nuthatches, and 18 species of warblers, including one Golden-winged Warbler, two Mourning Warblers, and two Blackburnian Warblers. It was chilly and lightly raining at times but the birds were active throughout the day, including lots of vocalizing. Full lists on ebird.
Also, FYI - roads into Little Bean Marsh CA (also in Platte County) are flooded and the site is not accessible (although you can see birds on Bean Lake from the dirt road before the flooding).
Kansas City, MO