Detective work: recent discoveries

My family tree is pretty solidly developed through my 2 X great grandparents on every branch, which is amazing! But on a couple of lines, I have hit a wall. I  started taking genealogy classes at the public library hoping to break through some of those walls. My new-found skills have actually turned up some enlightening nuggets of information.

While in class last week, I was browsing and half-listening while the instructor modeled a research example using census documents. The instructor explained an unusual feature of the 1930 census where the "age at first marriage" was given. I was in the back of the class, browsing my own family in the census when I came across an item for my great grandmother Ida Rene Bryant... in the 1930 Census, her "age at first marriage" was 16! I had only just recently discovered the shocking fact that she had been married at 19 to Lewellen Eley. Now I find that she had another marriage before that! That makes a possible fifth marriage for her. Her descendants only knew about two marriages.

Ida Rene Bryant's marriages
age 16 - ?? ??
age 19 - Lewellen Eley (divorced or annulled)
age ?? - ?? Williams (widowed)
age 26 - William Butler (widowed)
age 37 - George Abbott (my great grandfather)

Other dead ends that are driving me crazy:

Robert Scott Allen
Another brick wall is in the Allen line, my mother's maternal side. I have not been able to get past my 2 X great grandfather Robert Scott Allen. I believe his parents are John Allen and Rebecca Scott, but can't prove it with unimpeachable sources. I did find new information about Rebecca Scott, though, in her father's will.  Her parents are not who I thought they were. It was a case where two pairs of siblings married the same family. Her father and mother died when she was young and there is not much documentation about them.

John Dillingham and Calvin V. Crofford
The problem of John Dillingham's parentage is the subject of debate and speculation among his descendants on both sides of the ocean. My family lore says he was born in Wales and came to Indiana from Connecticut. Some say he was born in Providence, RI. His daughter Anna married Calvin Crofford (Crawford), but the Crawfords are a dead end as well.

George James Powell
My Nannie's grandfather. I believe he died after the war in 1865. I cannot find any documentation of his parents, though there are many connections with other Powells having the same unusual names, such as "Littleton" and "Bell". The Powells have a long history in Henrico and Accomack Counties.

These aren't the only brick walls in my research, but are the ones I am most anxious to resolve.