McGraw said in grinning eerie manner, Rowland diabolically wins biannually every tenner, which he achieves carrying black spangled banner during which stubbornly bringing home dinner.
The hidden message is:
WINNER, WINNER, CHICKEN DINNER.
An interesting observation:
The grid has four rows with seven images each. Some images are repeated. Now that was rather obvious. A more interesting observation is that the poem has four lines of seven words each, if we treat each punctuation as a separate "word".
That means that every word can be related to a certain image and vice versa. If so, all three punctuation marks correspond to the same image.
Let's assume that each motive represents a number that indicates the index of a letter to extract from the corresponding word. Perhaps the motives themselves give an indication of what the number is, but we can also work it out by reasoning about the word lengths: 1 is clear from the punctuation and 2 from the short word "in". There are two possibilities for 3 and 4, but if we take Long Island as 3 and the sand-coloured desert near the Four Corners Monument as 4, it doesn't look half bad.
After a bit of fiddling, we get these letter indices:6 3 2 4 5 6 1 3 7 3 5 1 6 1 4 1 4 1 5 7 4 1 3 8 7 4 6 1
McGraw said in grinning eerie manner , W I N N E R , Rowland diabolically wins biannually every tenner , W I N N E R , which he achieves carrying black spangled banner C H I C K E N during which stubbornly bringing home dinner . D I N N E R .
OP has confirmed that the images relate to the number somehow and the knowledge and geography tags support that. So the intended way to solve the puzzle is probably to identify the images to get the numbers.
The images are (top 1–4; bottom 5–8):
I find it very hard to identify many of the images, even now that I know what I'm looking for. (I assume that all eight locations are in the USA.) Other PSE denizens are better at identifying the satellite views, though. Thanks to their help, I have found:
1: One World Observatory, New York (@SQLnoob)
2: (unidentified (sub-)urban area)
3: Tri-State area between NY, NJ, CT (@cloudy7)
4: Four Corners Monument, New Mexico. (@SQLnoob)
5: (unidentified, but has a "5" shaped path in it.)
6: (unidentified urban area with park)
7: (unidentified rural area with fields)
8: (unidentified rural area)