According to Index Fungorum this species has been synonymized with the more recently published Conocybe albipes Hauskn.

Scott Bates tracked down the following info about this name change:

‘It looks like the use of Conocybe albipes Hauskn. is valid at this point for N.A. fungi formerly referred to Conocybe lactea (J.E. Lange) Métrod. [This is base on] Hallen et al. (2003)…. There is some discussion that is a bit cryptic and I don’t have Hausknecht 1998; however, I suspect the following:

Hallen et al. state, “Hausknecht (1998), working with European material, renamed C. lactea as C. albipes (G. H. Otth) Hausknecht 1998, because the basionym Bolbitius albipes G. H. Otth 1871 predates Galera lactea J. E. Lange 1940, on which C. lactea is based.” It sounds like Hausknecht synonymized several taxa that most likely had some negative implications for “C. lactea”. In looking for a new name to use Hausknecht found the earliest use in the Otth. name, but it conflicted with Bolbitius albipes Fr. (1863). But article 58.3 in ICBN (Tokyo code – see below) allowed for the adoption of a previous ‘illegitimate’ name. Because it is treated as a nomen novum, Hausknecht’s combination “C. albipes (G. H. Otth) Hausknecht” in 1998 should be properly cited as “Conocybe albipes Hauskn.” I am also assuming that the sentiment of Art. 58.3 is still valid today in the Vienna code (2005), but I am not positive.

“58.3. When a new epithet is required, an author may adopt the epithet of a previous illegitimate name of the taxon if there is no obstacle to its employment in the new position or sense; the resultant combination is treated as the name of a new taxon or as a nomen novum, as the case may be.”

But see:

Recommendation 58A – 58A.1. Authors should avoid adoption of the epithet of an illegitimate name previously published for the same taxon.’