Some embodiments include memory cells which have first and second metal oxides between first and second electrodes. The first and second electrodes include metal. The first metal oxide has at least two regions which differ in oxygen concentration relative to one another. One of the regions is a first region and another is a second region. The first region is closer to the first electrode than the second region and has a greater oxygen concentration than the second region. The first metal oxide includes one or both of hafnium oxide and zirconium oxide. The second metal oxide is directly against the first metal oxide and includes a different metal than the first metal oxide. There is a substantially linear continuous oxygen-concentration gradient extending across an entirety of the first metal oxide.